hot backup questions

I am starting to work with Oracle more and I need to learn about hot backups. We have a few clients that run 24 hour operatiion so the database need to stay running. Our databases are fairly simple. Where is there a good recource for learning how to implement hot backups. I'm not Oracle certified and am fairly new to this (basically I was handed this and told to 'make it work'). I've looked on the web and some of the articles I found just seem to go way over what I need.

Or basically what's the easiest way to backup a database without shutting it down? The tape backup program we use doesn't have provisions for Oracle so I need to figure this out. Now we simply use exports for backup (I know, not the best, but it has worked in the past for recovery purposes)

An important factor is also cost.

Backup And Recovery Concepts