I have been 'fishing' for about a year now, very unsuccessful. In that time I have caught one fish, a catfish, off a pier in North Carolina. It was about a foot and a half and was a blast to reel in.
I've been standing on the shore of the potomac casting hours on end with no luck at all. I have a Black Beauty 2 Rod and a Shimano R4000 reel, both of which I picked up from a local fishing/hardware store (very limited fishing supplies) for around $34.
When I fish, I usually stand across from Roosevelt Island, where I have seen other fishermen fish.
For my most recent birthday I was given four rapala lures. The 'original floater', 'fat rap', 'diver', and the name of the last one escapes me. They came in a kit called ultra lite rapala. Anyhow, I know these are more trolling lures but I figured I would go out and try them. No bites. They were not heavy enough to cast far out. During my time out there a boat passed by and caught six small fish, so I knew they were there.
I'm trying to teach myself to fish because its not really in the family. Its harder than I thought!
Back on topic. I talked to one of the fishers and he gave me some advice about shore fishing. He told me that using plastic, such as fake worms, is the best bet for shore fishing. He told me an offset hook(?) is good for using with the worm covering the hook so it doesn't get tangled on the weed. He said that every couple of seconds, pull it in a little so the worm jumps then floats down. He showed me that putting a triangular weight on the top and using that as a sinker is the best bet. He also said putting out stale marshmallows works great for small mouth!
Does anyone know what I am doing wrong? I've been out there so many times with nothing its starting to get frustrating!
A list of tackle, and supplies would be nice to have

Is my rod/reel bad?
How do I decide what size line to use? How does that affect the bait?
Why use leaders?
How do you decide what kind of knot/weights to use?
I have been searching the internet for a while now and really haven't found what I'm looking for. Any help is appreciated.
Thanks!
Paul