Key trouble

[AuToFiRE]

Now ive been poking around Ubuntu a bit since im more comfortable with it and i wanted to try out this key encryption thing. so i did and made a pgp file and whatnot. i exported the key to the same folder copied it to a usb drive and moved it to another computer, clicked on the asc key and gave me a message saying it was added( i opened up key manager and signed the newly added key) and then i tried to decrypt the file but i get the error
"Decryption failed. You probably do not have the decryption key."

So.. how DO i decrypt the files?