There are snap installation tools, some that are a punch and anvil type and some that work like a scissor(not good if the snap is to far from the edge of the material)they are both pretty easy to use, if the old snap pulled out i would recomend reinforcing it on the back side with another piece of material like denim.
check your local hardware store.
It's a snap!
1982 cj7. Frame off. shell valley kevlar body, stainless hinges, Bestop seats and supertop, KC titanium lights, Homemade swing out tire carrier with spare front wheel bearings/hub, Built 304,DUI,Edelbrock shorty headers with dual stainless 21/2 tubes into incynerator cans 21/4 dumped out the back,Edelbrock 600cfm, performer intake and cam, Borgeson lower column, Centerforce clutch, NV-4500, Dana 300 w/custom built twin stick, Homade 1/4" steel skid plate, 2.5 soft ride w/ 1" shackle lift, 33x12.5 mtr's. Stainless fuel and brake lines, Braided hoses. more...