Welcome back Judy! Don't give up- just keep asking away!
First off- I have PSCS so I hope this makes sense for you.
You actually don't need to turn a png file into a brush- you can use it *as is*. Some designers offer their brushes in a png format for users whose programs don't support brushes.
If you have your png file open and your layout open- you can just drag your png object right over onto your layout. Both windows have to be *smaller*- not maximized- hope that makes sense. I think some people copy/paste, but this is how I do it.
HTH

Holler if you need more help.