How do I "grow" bacteria for my science project?

The containers are called petri dishes. And dropping bread on the ground then putting it in a bag it will mold or spoil even if it hadn't been dropped on the ground. It will be easier to swab a slide than to try and look at the swab under the microscope. Below is a web site with project like what you want to do, with instructions. Look for the ones marked with an R, those include actual experiments you can do.