Is it at a real field, or someone's backyard?
If it's at a real field, yeah they have rental gear (all of it). You can buy paintballs from them too at bulk prices. Some fields have a rule agaisnt any paintballs aside from the ones they sell.
Some info for what to wear. A longsleeve short with a tshirt over it works well. Old cargopants or anything you're willing to get dirty work. For shoes, wear something with good ankle support, you'll need it.
This is assuming you're going to be out in the bush, not those speedball games