Hello Liji. Here are some minor edits and suggestions to help with your notebook entry.

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Hey guys,

I will go to Shanghai this week. If you have some free time, maybe we can hangout for a cup of coffee or something. We can practice the languages we are studying and learn from each other. I hope to see you soon.

this week [practice useing capital letters. titles used to capitalized all the first letter of every word]

hey[,]guys,

i will go to shanghai this week, [i should be always in capital letters] 

so if you have time , [no space between last word of the phrase and comma]

maybe we can hangout for a cup of coffee or something,we can [practise] practice languages and learning from each other,hope to see you soon [space between comma and the next word after it]

[period after the sentence]

You're English is fine. Just practie more in punctuations. Good luck on your trip!