Bulkhead fittings are better but it all else fails there are other alternatives. But now you want to regulate the flow of water. You can do this with something called a ball valve, gate valve or knife valve. They all do the same thing as the water faucet on the side of your house. They let you limit how much water goes thru them.
Lets start putting it together.
The pipe will have to be cut. With PVC almost any type of saw will work. A plain ole hacksaw will do best in most cases. Measure and cut your pipe and if possible cut the pieces a little larger than needed. When cutting the pipe be sure to clamp it to some sturdy surface by either clamps, locking pliers or a vise.