Sorry to break it to you, but the GT 630 is not meant for gaming.
^ that. May be hard to hear...but your system is not meant to game.
Well the CPU is good and 4 GB of ram should be able to handle most games.
Yeah that's true. Maybe "system" was the wrong word
Regardless, a gpu upgrade would help a lot. But if it is a prebuilt system, a PSU upgrade would likely be needed as well.