I played tennis today.

I arrived in Romania almost one a month now ago. Everything is goes going well till now so far. I like this country and the people here are friendly toward us.
Today we went to the center of the city to play tennis.  I have so long not played tennis for such a long time.  After two rounds of competitions with my colleague, I felt exhausted and was awared realise that I should take more exercise from now on.
Please help me to correct my daily journal, thanks in advance.

Remember "I" is always a capital letter.

"center" is correct for US English but if you are using British English it will be "centre".

Instead of "two rounds of competition" you coukd say "two games" or "two sets", I did not change that as it may have been that you were in a competition setting.  If it was one match then I would change it as stated. 

"should take/do more exercise" can be replaced by "need to take/do more exercise" 

"daily journal" could also be described as your "diary".

Enjoy Romania it sounds like a great place with plenty to do!

playing tennis today

I arrived in Romania almost one month ago.now, every things goes well till now, Everything is going well so far. I like this country and the people here are friendly to us.
Today we went to the center of the city to play tennis, I have (so long not play tennis) not played tennis for so long, after two rounds of competitions with my college, i felt was exhausted and was aware(d)that i should take more exercise from now on.
Please help me to correct my daily, thanks in advance. **

 I don't know if you mean to correct your diary or maybe the account of your day