It's a good idea to do some reading up if you are looking after community cats. Everyone has to learn and there's no shame in asking questions, but reading up does give you some basic understanding and knowledge, which is always good to have.
One thing for example is how to tell a kitten's age - a feeder wrote in today to say that she found a newborn and that it was abandoned. She said that the other feeders were trying to feed it milk, but it wouldn't drink and that it was eating canned food. She was really worried.
I explained that this meant the kitten was weaned, and that if it not weaned, it would not be able to eat at all. She wrote back to say that perhaps it was very hungry. After a few more emails, it turned out the kitten was a month or older. If she had read up a bit, she might have saved herself the panic.
There are lot of good resources - your library, the bookstore, or even the Internet.