First off, let me say I consider myself a beginner too. However, this site and a few other shows on TV have taught me a thing or two about using baitcasting reels, and I'd like to share them for others who are at least as new as I am.
First off, as the more experienced members have pointed out, you want a mid-range gear ratio to start off with; something like 6:1. This means that for every full turn of the crank, the spool turns six times. This is so that you get a good idea of how they work; lower ratios have more fighting power for stuff like large bass, higher ones are good for lighter fish like panfish and trout.
Next up, the line, don't overdo it; either on the weight or the amount. This means if the maximum pound test the reel is designed for is only fourteen pounds then that should be the maximum diameter you put on. If you want a stronger weight or better abrasion resistance, try a fusion type line or a braided line. They're thinner with a greater pound test rating. On a related note, make sure you use a rod that is compatible. Don't make the mistake I did years ago, and put a spinning reel on a baitcaster rod. Trust me, it doesn't work well. Though it can make for some downright comical moments at your expense.
Alright, on the actual operation of the reel. You'll note a knob on the right side as you're looking at the open face. This knob is for controlling the spool at the beginning of the cast. On the opposite side is a dial, probably labeled 1-10. This one is for the end of the cast. To set these, put a lure, or a weight if you know what weight you'll be using, on the line, hold the rod at about 30 degrees, and disengage the bale. SLOWLY adjust the right-hand knob until the lure or weight just begins to move. If you have it set right, the lure/weight will fall slowly and gently to the ground and stop once it touches it. Reel it back up, and adjust the dial this time, it should still fall at the same speed, maybe a little faster, with the spool going no more than a quarter turn this time before stopping. *Do not go out and try casting until you have this set correctly.* I did that and had to cut a whole spool of Spiderwire out because it backlashed so badly and I didn't know any other way at the time to deal with it. Remember also, if what I told you here and what the manufacturer says differ; follow the manufacturer's directions for how to specifically set these two functions, and remember to check each time you change baits. If you have it set wrong it can be disastrous for your fishing trip. Also, on the crank, you'll notice a star shaped piece of metal. For those who don't know, this is called a drag star. This is how you set your drag. Most folks recommend you set this at about a third of your line's test rating. I personally have mine set at about half, but that's because I use a tougher line and I'm usually fishing for the larger fish in private ponds and places that might not have seen a human footprint in decades.
http://www.youtube.com/watch?v=iWcAHgeWsUkhttp://www.youtube.com/watch?v=TDI5...re=relatedThat being said, once you have it all set correctly, go out and give it a few practice casts. Remember to feather the line with you thumb, and stop the spool with that same thumb just before or just as the lure or bait hits the water. This helps to prevent backlash and softens the impact of the lure on the water so you don't spook the fish.
If I've left anything out, or if you know a better way of doing something mentioned in here, please, SPEAK UP! I'm always open to learning new and better ways of doing things and I always try to pass on what I learn.