What's a good path to go down to begin with? I'm thinking exploration.
Which race did you choose and what sort of gameply do you enjoy?
EDIT 2: So uh, how do I trade?
1) Trading can/does occur remotely: just because you are at station X when you buy, sell or list something does not necessarily mean that the item you bought or sold (or listed) is at station X.
2) Most of the item listings you see are being bought/sold/listed by players in the game, not npcs.
3) Trading is not limited to items currently available. For example, if you see a buy order for a widget, that means that somebody wants to buy a widget. They obviously don't have a widget. Though note that the game does not have short selling.
4) The player making a listing chooses the price. Others choose whether they wish to accept the offer. Consequently, there isn't always a direct correlation between buyers and sellers. For example, if Bob has a widget he wants to sell, he might list it for 100 ISK. Just because he wants to sell for 100 ISK doesn't mean that anyone wants to buy at that price, so he places a sell order for 100 ISK, and the item becomes listed. Next, let's say Alice comes along and she wants to buy a widget. But she only wants to pay 80 ISK, not 100. So she sees Bob's order, ignores it, and places a buy order for a widget, offering to pay 80 ISK. There is now one buy order and one sell order, but no orders have been filled.
5) Note that some order types and distances might require certain trade skills to execute. For example, you start the game able to make remote buy orders, but not able to place remote sell orders.
I've bought some antibiotics and jumped to a station that supposedly has a buyers offer for
them, but when I try it says the broker failed to find the offer?
It's possible the order was filled after you saw it, but before you accepted it. Or that the buyer changed his offer.