Peers are other users who are either downloading or "seeding" the same file as you.
Seeds have a copy, or part of a copy, of the file you need and are providing it to you.
Leeches are anyone downloading the file. But not necessarily without seeding.
So seeders are the most important link in the chain when using torrent clients. If you have no seeders, you have no file. There is no way to get more seeders without another user having a copy of the file and seeding it. In general, P2P is a very slow way to transfer files. That's just the way it is.
*Make sure you virus scan everything you download before using it*.
Check the website in the source for more detailed information.