Bread-Bakers v108.n019.5

I want to make light long Italian or French bread that is light for 
sandwiches. I tried the rise over night. The bowl was in a plastic 
bag no air closed tight. I shaped the loaves on the cookie sheet and 
stuck them in a big plastic bag and maybe didn't let them rise long 
enough. Baked at 400F for 30 minutes and inside was doughy and heavy. 
I have been searching the net and find that in order to make light 
airy bread you need to rise fast at a warmer temp. What should I do?