please help me find out how to export file thats been recorded.

You checked the Help-files for "Export"? Is there something specific in the process you have problems with?
The MP3 encoder is free nowadays, but IIRC you need to do something to get it (depending on which version of SONAR you're using). I have never used it so I don't know details. Someone who knows will surely chime in.

Search for "mp3 decoder" on the main cakewalk site and you can probably find the free version to download.

Did you select the clips you wish to export?

You should list what you have tried to do, this would help us better understand what you may have missed in the export process.
I find questions like this to be the toughest. because we have no information to go by, just "Please Help".
https://www.cakewalk.com/Documentation?product=SONAR%20X3&language=3&help=Dialogs1.45.html
 
https://www.cakewalk.com/Support/Knowledge-Base/2007013077/Basic-File-Exporting-for-Audio-CDs

Everyone has provided the answer.
You can do it.