*English is not my native language but I've started to pick it up since I was 5. I am quite confident with my English but still, I might also make some mistakes. I will "correct" some of your sentences but that doesn't mean that you're wrong. I just reckon that maybe it's better to write in another way.*

Good morning everyone. I speak about happy university life which spend with my friends
I would like to share my happy university life which I spent with my friends.

I have in mind a friend
*I suppose this is a title, so it should be written as "A friend in my mind"*

In my world, family and friends are very important there.
my family and friends played very important roles.

Family, is the best choice when I want to be comforted.And friends, it is those who occupy most of my time and I grew up together and.
Family is my best choice for seeking comfort when I am feeling sad, dealing with frustrations or struggling with adversities. Friends are those who grew up with me and occupied most of my time.

I am a student of Sabaragamuwa University. At university, my friends to accompany me through almost all the time.
In the university, my friends accompanied me most of the time.

Whether happy or sad, we have been together.
No matter happy or sad, we had been together.

We went out to dinner to discuss the beautiful clothes together, side complained filled out the job.
We went out for dinner, discussed over the clothes, complained and grumbled while we were doing our work.

I cannot imagine, if I can only stay in university a person, then how can I spend so long years.
how could I spent such a long time in university if I were alone.

We dance, sing, eat, learn, come and go, take pictures, sleep and awake whole nights.
We danced, sang, ate, learned, walked, took pictures, slept and stayed up all night long.

We did everything together. We are making memories for years.
We have been creating memories for years.

So, in my mind, a friend means that no matter when and where, you will accompany and happiness!
In my opinion, a friend will always accompany me and bring me happiness whenever and wherever I am.

This is the happy university life which I spent with my friends.

我在大学跟朋友们在一起的快乐生活

您好！我叫lakna。我想和你们分享我在大学跟朋友们在一起的快乐生活。

我想和你们分享（经验，故事等等等）: I would like to share (experiences/ stories etc.)

我心目中的朋友

*I suppose this is a title, if not then it's wrong*

在我的世界里，家人和朋友是无比重要的存在。家人，是在我希望得到安慰时最好的选择。而朋友，则是那些占据了我大部分时间并且和我一起成长的人。
我是sabaragamuwa大学的学生。

在我的大学生涯中，我的朋友陪伴我度过了几乎所有时光。

我的大学生涯：My life in university

无论是开心还是难过，我们都一直一直在一起。我们一起去吃饭，一起给衣服作出评价，一起边抱怨边写作业。

I won't say "讨论漂亮的衣服" is wrong but it's weird to use the word "讨论" for clothes.
When you say you're discussing over the clothes, for me I take it as at first you and your friends saw some clothes, and then you making discussion and giving opinions. After that you and your friends make conclusion and rate the clothes if they are beautiful. So I use the word "评价"

我不敢想象如果我只身一人呆在大学，该怎么度过这么长的岁月。

只身一人: alone

我们一起唱歌跳舞、吃饭、学习、散步、合照、睡觉，甚至彻夜未眠。

It's totally wrong to put "来了又走" here. I suppose that you try to say you are strolling with your friends, so I use "散步".

I use the word "合照" is because I reckon you try to say you take pictures with your friends, which means that you and your friends are in a picture.
If you use the word "拍照", it means that you have a camera and your friend also have one camera. Both of you go to a place and take your own picture. It's more like both of you are photographing together.

I am sleeping. : 我正在睡觉。(睡觉 is a verb)
I am lack of sleep.: 我睡眠不足。(睡眠 is a noun)

You can say 保持清醒整整一夜, but 彻夜未眠 is better. Both of them have the meaning of "stay up all night long"

我们一起完成所有的事。

*We did everything together.*

It's better to use "完成" instead of "做" in this case

这些年，我们共同创造了许多回忆。 

*For all these years, we created a lot of memories together.*

You wrote "我们正在回忆多年" means that you and your friends are rewinding or recalling the memories in the past.

因此，在我心目中，朋友意味着无论何时何地，都会陪伴着我并带给我快乐。 

I suppose that you want to define friends and your definition is a friend will always accompany you and bring you happiness.
You wrote"你都将与快乐相伴" means that "your friend will be accompanied with happiness".

这就是我和我的朋友一起度过的快乐的大学生活。 

The word "spend" in Chinese is "花", but the verb "花" is not suitable in this sentence.

I don't know how to explain the differences between "花" and "度过", so I give you some examples:
花钱：Spending money
花时间：Spending time
我花时间做运动：I spend my time doing sport
我在大学里度过的时光：The time I spent in the university 

我在大学跟朋友们在一起快乐的生活

您好！我叫lakna。我说我在大学跟朋友们在一起快乐的生活。
我心目中的朋友
在我的世界里，家人和朋友是无比重要的存在。家人，是我希望得到安慰时最好的选择。而朋友，则是占据了我的大部分时间并且和我一起成长的那些人。
我是sabaragamuwa大学的学生（or sabaragamuwa的大学生）。在大学，我的朋友陪伴我度过了几乎所有时光。无论是开心还是难过，我们一直一直在一起。我们一起去吃饭，一起讨论漂亮的衣服，一起边抱怨边写着作业。我不敢想象，如果，我只能一个人呆在大学，那我该怎么度过这么长的岁月。
我们跳舞，唱歌，吃饭，学习，来了又走，拍照，睡眠和清醒度过整整一夜。我们在一起做所有事情。我们留下了值得珍藏多年的回忆。
因此，在我心目中，朋友（最好修改为友谊）意味着无论何时何地，你都将与快乐相伴！
这是快乐的大学生活，我和我的朋友共同度过。

Good morning everyone. I speak about happy university life which spend with my friends
I have in mind a friend
In my world, family and friends are very important there. Family, is the best choice when I want to be comforted. And friends, it is those who occupy most of my time and I grew up together and.
I am a student of Sabaragamuwa University. At university, my friends to accompany me through almost all the time. Whether happy or sad, we have been together. We went out to dinner to discuss the beautiful clothes together, side complained filled out the job. I cannot imagine, if I can only stay in university a person, then how can I spend so long years.
We dance, sing, eat, learn, come and go, take pictures, sleep and awake whole nights. We did everything together. We are making memories for years.
So, in my mind, a friend means that no matter when and where, you will accompany and happiness! This is the happy university life which I spend with my friends.