Diary of my life in Canada　July 30

Diary of my life in Canada　July 30

*"Wedding party" sounds fine, but it is more natural to only say "wedding". 
**If you say "take pictures with", it means that you are going to appear in the photo (along with the CN tower, for example). If you want only the CN tower to appear in the photo, you have to say "take pictures of".

Nowadays*, I have** some problems.
When I talk to someone, I can't focus on my English.
I try to do that, but I'm a shy. So I can't stop thinking that about how what they are thinking about me.
I care their mind about what they think too much, so I became become*** nervous when I talk to someone.
I can speak if the person is my best friend, but I usually can't do**** that.
How What should I do? How can I overcome this problem?

*"Nowadays" sounds old-fashioned to me, but it is not incorrect. Maybe it is more natural to say "Recently". 

**Since these problems are ongoing, it sounds better to say "I have been having some problems. / I've been having some problems. "

***It sounds more natural to say "So I get nervous". In this sentence, get means the same as become, but it sounds more natural. 

****You need to use a verb between can't and that. 

And another problem is my pronunciation.
Because of this problem, it would be hard to communicate to my classmates.
Especially, South American people.
I'm from Japan, so I can communicate to Asian people such as Korean or Taiwanese.
We learn English together , so it means we are talking with in our second language.
So If my classmates say "Sorry?", I will be afraid. It means, they couldn't make sense of what I said.
But it's natural because we're not native and we're learning English right now. It will be happen for to everyone. I just don't have any confidence. I know, if I want to have a confidence, I have to make mistakes when I speak English. The only way that I can do it is talking to people in English!

Yes! Practice makes perfect! Although there are some small mistakes, I could understand everything that you wrote. You can communicate very well in English! 

I'm not going to correct the whole thing because that's often confusing.  Here are a few things to focus on:

One of my friends will get married this September, but I can' t go the wedding party because I'm in Canada.

You have a group of friends (plural) and one of them will get married.  That works for anything, not just friends.  One of my shirts is stained.  One of my shoes is missing.  Notice also that the verb matches the singular "one" which is the subject. 

When I talk to someone, I can't focus on my English.
I try to do that, but I'm a shy. So I can't stop thinking that how they think about me.

Feeling shy about using a new language is normal!  Remember, a foreign accent is a sign of bravery! You are brave, but you don't know it yet! :)

I care their mind too much, so I became nervous when I talk to someone.

You wouldn't use "I care" here.  Maybe "I worry about what they think" or "I worry too much about what they think..."

I can speak if the person is my best friend, but I usually can't do that.
How should I do? How can I overcome this problem?

So If my classmates say "Sorry?", I will be afraid. It means, they couldn't make sense of what I said.

Do not be afraid!  You are doing very well!  And most Americans think foreign accents are beautiful and exotic.  Nobody will laugh at you!