If it's a good tent, repair it. That said, if it's old enough that you tore it just unpacking it, expect more damage soon.
Repairs are simple, using a cloth tape for a smaller tear, or sewing first for a larger one then using the tape. You'll need to use seam sealer after, and make sure you use the right type for your tent fabric. Make sure too that the seams are smooth, so they don't pool water.