Well it's july and finally my vacation arrived.

Well it's July and finally, my vacation has arrived.

Well it's July and my vacation has finally arrived. 

But the problem is: what I gonna do?

But the problem is: what am I gonna do?

Well my familly don't want to travel and most of my friends are travelling so i'm here alone and with nothing to do.

Well, my family doesn't want to travel and most of my friends are travelling, so I'm here alone and with nothing to do.

But at least I have the internet to save me from the boredom.

But at least I have the internet to save me from (the) boredom.

And now i'm here writing this in english because i think i need to improve my fluency in english obviosly.

And now I'm writing this here in English because I think I need to improve my fluency in English, obviously.

It's better waste time in something useful than with games, social medias or whatever.

It's better to waste my time with something useful rather than with games, social media(s), or whatever.

My tedious vacation

Well it's July and finally my vacation has arrived. But the problem is: what am I gonna do? Well my family don't doesn't want to travel, and most of my friends are traveling, so I'm here alone and with nothing to do. But at least I have the internet to save me from the boredom. And Now I'm here writing this in English because I think I need to improve my fluency in English, obviously. It's better to waste time in something useful than with games, social medias or whatever.

"I", when referring to yourself, is capitalized, along with the name of the month (ie July). 

It's also strange to start a sentence with an "and" or "but". It can be done on occasion, but it's best NOT to start it that way.

Sorry that you can't go on an exciting adventure during your vacation, but I'm glad that you have decided to use your vacation time in a useful way. I wish you the best in your English studies!

My tedious vacation

Well it's july and finally my vacation arrived. But the problem is: what am I gonna do? Well my familly doesn't want to travel and most of my friends are travelling so i'm here alone and with nothing to do. But at least I have the internet to save me from boredom. And now i'm here writing this in english because i think i need to improve my fluence in english obviosly. It's better to waste time in something useful than with games, social media or whatever.