Hi Abdulhaseb,
As the Nokia 2700classic is a Series40 phone, it does not support full multi-tasking. If there were instances where Series40 has supported multi-tasking, it is very rudimentary support and I'm presuming limited to only the built-in system apps and not other third-party apps (such as those available in the Nokia Store).
If you wish to have a handset that supports multi-tasking, your best bet would be to use Symbian or Nokia Lumia handsets. AFAIK, even Asha series does not support multi-tasking. Correct me if I'm wrong.