Hey...weren't we all clueless at one time?
The way to tell if your arrows have a helical on them or if they are straight fletched is look straight down the arrow from the nock and see if you can tell that your vanes are "wrapping" around your arrow. If they are, then you have a helical. If you can't see much of the vane, then you probably have only a straight fletch. As txjourneyman said, the helical will spin your arrow faster, resulting in an arrow that stablizes faster. This will give you better arrow groupings. You may not be able to tell a whole lot of improvement when shooting a target tip, but when you are shooting broadheads, your arrows will start to group together a little better with a helical. Here is a link that has a pic of arrows that have a right helical:
http://www.archerytalk.com/vb/showthread.php?t=523713&highlight=helical
The bitz fletching jig is a little pricey, but you have so much control on how much helical you put on the arrow and you can fine tune it for your set up. I would start off by putting as much helical as you possibly can, making sure the base of the vane stays in contact with the shaft and go from there. It may take several tries, but you will get a setup that will work great for you...