Sorry, I ignored 2 more mistakes in your writing last night. Here we go.

You can message me if you're from the country that language  I'm not able to pick up your language...as long as you know some English.

It should be corrected in the following way.

As long as you know some English, do message me even if you're from a country,  the language of which I'm not able to pick up.

IJust want to say... :D

Hi everyone!
This is my second entry, I just gonna write about my purpose to using iTalki.
It's that I just want to make friends around the world. You can message me even you're from the country that I'm not able to learn your language...if you know some English. It's no problem ^^
moreover we can share our knowledge and things. although I'm not seriously to learn the language but we can just talk.... it good enough ^____^
I like to talk with foreign friends and make new friends. feel free to follow me then I will follow you back. 
  

My suggested version:

Hi everyone!
This is my second entry, I just gonna talk something about my purpose of using iTalki. 
That is to make friends around the world. You can message me even if you're from the country that I'm not able to pick up your language...as long as you know some English. It's no problem ^^
Moreover we can share our knowledge and things. although I'm not serious in learning the language, I found it really interesting and great to chat with someone as language partners on such a maverlous forum.

 Just talk to me! I like talking with foreign friends and make new friends. Feel free to follow me, and I will follow you in return for your being friendly. 

Notes: 

1. We never use though and  although together with and or but

2. talk something about sounds much more oral， while write about sounds too formal

3. we either say "be serious in/about sth" or say"be serious in doing..."

4. here by inserting "Just talk to me! " , we could add up the coherence of the whole context

......