If it's a USGI Carbine, the makers name will be stamped on the receiver right behind the rear sight.
On some GI Carbines the rear sights over hang the maker's stamp to the point where it's difficult to see it.
The serial number will be stamped behind the rear sight, to the rear of the maker's stamp.
If there is no maker's stamp behind the rear sight, it's not a USGI Carbine, it would be a commercial made rifle.
However, most commercial makers also stamped their name right behind the rear sight.
If it's commercial it may have the makers stamp on the left side of the receiver, possibly below the wood.
Also look for any stamps just behind the front sight. The maker of the barrel usually had a stamp and possibly date there, but that's not necessarily the maker of the receiver.
Somewhere on the receiver will be a maker's stamp and serial number.