I've never even touched a fly fishing rod before and i'm going fly fishing this weekend for large and smallmouth bass. I have no idea what kind of flies to use in certain conditions and I have no idea how to work the flies. Do you drag 'em across the surface? Do you let them sit? i don't know. I don't even understand how to cast the thing. Please let me know if you have any answers.

First are you on a lake or moving water(river, stream)  If you are on a lake try top water poppers in a larger size so the blue gill will leave it alone.  next most streamers (large fly that imitates a baitfish) you cast out then use the line to pull it back under the surface kind of like working a jerkbait back.  On the cast don't try to force it just let the weight of the line pull out once you let it go.  Hope this helps I haven't been fly fishing in years but I can remember some of it.

yeah it's a private lake with overpopulated bass

Go with the poppers first get a larger one that way you can get a little help from the lure with the casting.  The popper you work just like a any top water bait you are used to using.  Three short tugs then let it set.  I have caught a lot of bass on them but they also get hit by the bluegill alot.  But it is a lot of fun to catch any fish on one.  good luck

when i go to the store how do i know what a popper is

Most poppers look like this:

http://www.basspro.com/webapp/wcs/stores/servlet/Product_10151_-1_10001_3159_175002003_175000000_175002000_175-2-3

Gotta be real honest with ya, flyfishing is not a technique you pick up in a few minutes.   Suggest you practice at home about a half hour every day for a while.  Strongly consider hiring an instructor.  An hour of guided instruction will go a long way towards proficiency.  Even an instructional video is very helpful, sometimes local libraries have them or they are available from Netflix if you're a member.

The key to fishing poppers is patience:  Present your popper then let it sit for as long as you can stand (about 1 minute in my case!)  Then just twitch it, let it sit some more.  Work it with short twitches using your line hand not your rod tip then (drum roll please) let it sit.  The key to flyfishing is presentation.  Don't work your lure like you would with a BC or spinning rig.  

Hope my comments don't come off as snobbish or condescending, using a flyrod is a wonderful way to fish but it does require more effort to learn.  I doinked around with it for years, acquiring bad habits along with good ones without really understanding what I was doing.  A half-hour of instruction with a pro (something I normally avoid) just a few months ago really enlightened me.  also it's helpful to videotape your practice sessions so you can see exactly whats going on.  

When you catch your first bass on a flyrod you'll understand the allure.  It has some kind of primal attraction that's difficult to articulate.  Let us know how your weekend turns out and wether you're going to stick with flyfishing.