wicat3

Hey guys I know this has been gone over a few times and there are some great posts on it but i have a few questions that i have not seen covered. I have a smalll cheap welder from tractor supply that seems to do alright so far and i have a little sheetmetal skill. I have a few patches of floor that is rotted out and it appears at sometime someone put some putty stuff down to cover the holes so im planning on patching the rusted areas after cutting the rust out and then sanding the floor pan and applying an anti rust protective coating on the floor then placing new carpet down at sometime. My question is whats the best way to weld the panels in place? Im new to welding and know enough to get introuble and wasnt sure if i should drill holes in the patch panels and weld the holes or just tack the outside patch to the existing floor? I want to seal all the patch welds and panels with an rtv chaulk to seal it before the protective coat.