Well I don't have any, but everyone around me does. LOL. Anyways - to manage it, well you have to pay it on time and know your spending limits, apr percentage, and grace period. Basically you should read all the fine prints that comes along with the CC. I know most people don't, but it's a good idea to.
APR rates (interest) are usually high if you're just starting out, but eventually it can go down and if you continually pay it on time. The grace period does help. If you don't know what that is - it's when your payment is late - each company has different grace periods...so say yours is 25days well you have 25days before they'll charge you extra fees for being late. It's usually best to pay it between the 25days. And even better if you pay the full amount...paying just the minimun balance causes the APR rates to stay the same.
Oh and a tip for anyone else who has a really really high APR rate and it doesn't seem to go down, sometimes you can call the CC company and ask them if they can lower it a bit or lie and say there's another company that's willing to offer a lower one - it usually works.
And as for the credit score - basically if you maintain paying your bills on time for anything from CC to car payment, utilities you should have a good credit score. You can always get a free credit report online on one of those sites to be sure they don't have anything wrong on there. I knew someone who had his dad's info on his because they have the same name...so always a good idea to look into that too. Hope this helps a little.
...maybe someone else can add on if they know more. But of course, I might just be stating the obvious if you had already known this and I don't have one. Hehe...