Kenna did a great job at correcting, but she missed a few points. Here is my correction. The corrections are in red, while the points she missed are in yellow green.

Hello. I'm 31-years-old and living in Seoul. I would like to chat with people from all over the world, but actually my English is very poor. I decided to study English for myself. Nevertheless, I feel that it's needed necessary to teach me from learn English from a nativer. I also hope to meet some good girls from other countries for to start a new life...

Notes:

1.) In "31-years-old" the dashes (-) are not necessary, but they are a more proper way of writing out one's age.

2.) It's is a contraction for the words "it is". You do not put an apostrophe (') only when talking about possession. Example: The book is very good. Its theme is to never give up.

I hope I did a good job. If you notice that I have many any error whatsoever, please correct me. This was my first correction. :) Keep practicing your language. My correction was a bit different, but the wording is correct in both mine and Kenna's versions.

Hello Jaesam,

   It is great that you want to continue learning English. If you ever need any help, please let me know!

Hello. I'm 31 years old and living seoul. I would like to chat with people from all over the world. but actually My English is very poor, so I decided to study English for myself. Nevertheless, I feel that it's needed to teach me from learn English from a native. I also hope to meet some good girls from other countries for new life...

  You did a really fantastic job! Keep up the hard work, and good luck!!

Sincerely,

Kenna