it probably just snaps in. shouldn't be too hard to figure out, when you pull the old one off, to install the new one. all the best!
You've dislodged a couple of underbody panels there. They're held on with a mix of 10 mm bolts (socket size), self-tap screws (into nylon push in bits) and push in fasteners. Hopefully it's just a few fasteners missing (if any) and the panels can be refurb'ed. The passenger side fasteners should be symmetrical, for reference. If you can get the front on jack stands or ramps it's good enough for access. I had the centre one off the other day, this is all the fasteners on it: The front corner piece connects to fender liner, and that connection rusts right up, at least with ours. I don't have decent pic of fasteners but you just get in there, will figure out:
