Luz, you're already ahead of the game - you PRACTICE!! Also, if there is a Power Squadron (kind of a Coast Guard auxilliary group) chapter near you, they offer a basic boating course that's worth taking. Gives you basic knowledge of stuff, including how to anchor.
The way I learned was to cruise around the anchorage a couple of times to figure out where you want to be, allowing for depth and swing distance, in case of wind shifts. Stop the boat at the point you want the anchor to be (heading upwind), drop the anchor, and back up. To calculate the amount of line (anchor rode) you want out, take your depth, plus the distance from your deck to the water, and multiply that by at least 7, even 10. That's how much anchor rode to let out. If you still drag, let out more line - "When in doubt, let it out." Back the boat up at about 1300 to 1500 rpms, and when the anchor bites, you'll feel it, and the anchor person will see the line go taut (sp?). If the anchor drags, the line will kind of jerk or skip - rather obvious. If you can't get the anchor to bite, pick it up and try again. Don't worry about how many times you need to repeat that process - you need to feel comfortable that you're holding.
When my wife and I first did a bareboat charter just the two of us, she wanted to try the helm when we anchored. We came into a beautiful little anchorage on Anguilla near St, Martin (with several boats already there). I manned the anchor, and i told her when we got the the spot where i was going to drop the anchor, I'd tell her to stop, and she was to put the boat in reverse to stop. I'd drop the anchor, then she was to back up until the anchor bit. Well, we got to the point I wanted to drop anchor, I told her to stop. The boat still moved forward. I told her again to stop, but the boat still moved forward. Finally, I went back and told her close up put the boat in reverse. She said, "Look, I did!" Well, it was in reverse, but only at idle speed. I then, in my diplomatic and quiet fashion, said, "This is a 12 f***ing ton boat!! You need to put the damn thing into reverse A LOT!!!" at which point a lovely Frenchman came out of his cabin and said "Bon soir! A beautiful evening, no?" Again, one of those moments we laugh about to this day.
You'll be fine.