I downloaded windows 8.1, thinking that I'd be able to upgrade my 32 bit system to 64 bit. If this is not possible tell me, but if it is possible please help me out.

To change from 32bit Windows to 64bit Windows a clean install will be performed.

I shall suggest you to go through the following thread:

http://answers.microsoft.com/en-us/windows/forum/windows_8-windows_install/how-to-migrate-my-windows-8-upgrade-from-32-bit-to/6eea0525-8ab1-4d94-9334-3d4bfdcefd94