Stand in the tent with lights off in the tent and bright light on outside the tent. Close the tent with you in it, note the light leaks, Duct tape them. If it's coming through the zipper, hang a cloth in front of the door. I have a tea towel that hangs over where the two zippers meet just to be safe.
@Cap Stone im growing it in my room will it be
I read somewhere awhile back that people were filling pin holes in their tent with glue? Not exactly sure what type of glue or how exactly they did it, just something I remembered reading.