You did a great job as a beginer studing Chinese though there are some little mistakes about the charactors and tones. But don't worry about them, even Chinese people make these mistakes and we even don't realize :D

"First Mandarin Lesson" - Cheat sheet =)

Hello! How are you?
你好吗？
ni3 hao3 ma5?

I'm very good thank you, and you?
我很好，谢谢。你呢？
wo3 hen3hén hao3, xie4xie5. ni3 ne5?

I'm also very good thank you. The weather is very nice today.
也很好。今天天气很好。
ye3 hen3 hén hao3. Jin1tian1 tian1qi4 hen3 hén hao3.

【?3+?3】 when the 2  characters are both 3, then the former one should change into 2

for example,  【管guǎn  +  理lǐ】 should change into 【管理 guán lǐ】 it means "manage"

What are you called?
你姓叫什么？   

Ni3 xing4 jiào shen2me5?

【姓什么？】 asking about family name  

【叫什么】 asking about your name， if the answer is a Chinese name, usually you say your full name, that's familly name and given name. for eaxample， wo3 jiao4 李li3（family name） 明ming2（given name）.

My name is Arthur.
我叫 Arthur。
wo3 jiao4 Arthur.

Where are you from?
你是哪国人？
ni3 shi4 na3 guo2 ren2?

I come from England Are you from China?
我是英国人。你是中国人吗？
wo3 shi4 Ying1guo2 ren2. ni3 shi4 Zhong1guo2 ren2 ma5?

Why do you want to learn Mandarin?
你为社什么想学普通话？
ni3 wei4she2 shén me5 xiang2 xue2 pu3tong1hua4?

【为什么 wèi shén me5】 is the only way to write and pronunce.

I have only learned a little, I want to learn some more!
我只学过一点。我想知道的得更多一些。
wo3 zhi3 xue2guo4 yi1yì dian3. wo3 xiang3 zhi1dao3 de geng3 duo1 yi1yì xie1.

【更多】is a complement, so the "de" before it should be 【得】

Can you speak any English?
你会说英语吗？
ni3 hui4 shuo1 ying1yu3 ma?

Yes. I can speak a little English.
会。我会说一些英语。
hui4. wo3 hui4 shuo1 yi1yi4xie1 ying1yu3.

No. I can't speak that language.
不会，我不会说这种语言。
bu4 hui4, wo3 bu3 hui3 shuo1 zhe4 zhong3 yu3yan2.

I'm sorry。 Please could you repeat that a little slower?
对不起。请你能再说一遍慢？ 请你慢点再说一遍, 行吗？ qǐng nǐ màn diǎn zài shuō yí biàn, xíng ma?
Dui4bu4qi3. qing3 ni3 neng2 zai4shuo1 yi1bian4 man4?

Here is the ways to say 【一】in mandarin:

1 when you counting numbers 12345 or it is at the end ,  it is 【yī】  专一 【zhuān yī】

2 when 【一】 is before a 【4】  it is 【yí】  for example:  一半 【yí bàn】 

3 when 【一】 is before a 【1/2/3】 it is 【yì】 一天【yì xiē】 一年【yì nián】 一点【yì diǎn】

I didn’t understand. I don’t speak much Mandarin.
我不明白。我不会说很多普通话.
wo3 bu4 ming2bai2 bai5. wo3 bu4 bú hui4 shuo1 hen3duo1 pu3tong1hua4.

Thank you so much!
太谢谢你了！
tai4 xie4xie4 xie5 ni2le5!

There are lots of words which has the same characters, the second one shoud be 5

for example: 妈妈 māma5(Mom)  爸爸 bàba (Dad)  看看 kànkan (look)

 
Good bye!
再见！
zai4jian4!

Here is a pice of advice : If this is a "Cheat sheet" for Chinese exam, you could ignore some of my corrects and refer to your book and note. Because maybe your teacher will grade according to text book. That's what I do since I am learning English :D

These corrects are according to my Chinese books and learned from my Chinese teachers. Hope I  helped you with your Chinese study. 

"First Mandarin Lesson" - Cheat sheet =)

Hello! How are you?
你好吗？
ni3 hao3 ma5?

I'm very good thank you, and you?
我很好，谢谢。你呢？
wo3 hen3 hao3, xie4xie5. ni3 ne5?

I'm also very good thank you. The weather is very nice today.
我也很好。今天天气很好。
ye3 hen3 hao3. Jin1tian1 tian1qi4 hen3 hao3.

What are you called?
你叫什么？
Ni3 xing4 shen2me5?

My name is Arthur.
我叫 Arthur。
wo3 jiao4 Arthur.

Where are you from?
你是哪国人？
ni3 shi4 na3 guo2 ren2?

I come from England Are you from China?
我是英国人。你是中国人吗？
wo3 shi4 Ying1guo2 ren2. ni3 shi4 Zhong1guo2 ren2 ma5?

Why do you want to learn Mandarin?
（here you should answer 是 or 不是）你为什么想学普通话？
ni3 wei4she2me5 xiang2 xue2 pu3tong1hua4?

I have only learned a little, I want to learn some more!
我只学过一点。我想知道得更多一些。
wo3 zhi3 xue2guo4 yi1dian3. wo3 xiang3 zhi1dao3 de geng3 duo1 yi1xie1.

Can you speak any English?
你会说英语吗？
ni3 hui4 shuo1 ying1yu3 ma?

Yes. I can speak a little English.
会。我会说一些英语。
hui4. wo3 hui4 shuo1 yi1xie1 ying1yu3.

No. I can't speak that language.
不会，我不会说这种语言。
bu4 hui4, wo3 bu3 hui3 shuo1 zhe4 zhong3 yu3yan2.

I'm sorry。 Please could you repeat that a little slower?
对不起。请你慢慢地再说一遍 
Dui4bu4qi3. qing3 ni3 neng2 zai4shuo1 yi1bian4 man4?

I didn’t understand. I don’t speak much Mandarin.
我不明白。我不太会说普通话.
wo3 bu4 ming2bai2. wo3 bu4 hui4 shuo1 hen3duo1 pu3tong1hua4.

Thank you so much!
太谢谢你了！
tai4 xie4xie4 ni2le5!

Good bye!
再见！
zai4jian4!