I guess this is part two of the stuff I have to get out of the way. The mechanics of trading are a little bit hard to grasp. The market is divided between buyers and sellers. Players put up "buy orders" for items, and another player can fill this order. They can also decide to put things up for sale, and hope someone comes along and buys it.
The first thing anyone should do is orient yourself. The comparison here is the overview. A pvp pilot won't try to pvp with a screwed up overview, and a miner won't try to mine without having asteroids in their overview. Why would a trader have a screwy looking market tab.
To get started, when you open up your market you will see two sections, buyers on the bottom and sellers on top. Generally, you want to orient yourself so you see the cheapest sellers and the most expensive buyers. You do this by clicking on "Price".
Now to explain the BASIC concept of trading. You put up a "buy order" so that your offering the most amount of money for a item, and then putting it up for sale so your the lowest "sell order". The easiest way to explain this would be taking a item, we will say hulks. Lets pretend that there are hulks for sale for 197m, 196m, and 195.9m isk. and buy orders for 150m and 151m. This means that there is a gap of 35m, which could be your profit. There is also the variable of range which will be discussed later.
Buy Orders and sell orders ALWAYS get filled by price. A player will ALWAYS buy the cheapest ship (even if they want to play more) and sell to the most expensive buy order. So if we use our hulk example: If you put up a buy order for 151m - .01 isk, then your order wont be filled until the 151m is filled. If you put up a buy order for 151m +.01 isk, then your order will be filled first.
The issue of range is the other major variable. Your buy orders can have a range of "region", and anyone in the region can fill your order. The problem is that items don't magically move, so if you buy something 10 jumps away you have to go 10 jumps to go and get it.
I realize that I probably butchered the mechanics of trading, but this has been explained so many times before. I figure I will just post links.
I recommend reading:
http://eve.grismar.net/wikka.php?wakka=TradeBasics - good and simple explanation