I am new to bitcoin, and GUI miner won't work on slush's server I am new to using bitcoin, and I don't have any mining hardware, just my computer. I got GUIminer, and set the server to other, and the host name to http://api.bitcoin.cz, port 8332. I entered my username and worker name, and it's now mining (very slowly, as expected) but still mining, however, it says on slush's server that i don't have any active workers and I'm not mining, anybody know what the problem is? I also have 1 stale share, what is that, and how did i get it?
Your hashpower is magnitudes too low. It is so low, that the pool doesn't accept your work, because it will never amount to any use. You are competing with a teaspoon in a world of Bucket-wheel excavators. You will be expending energy and never gain any revenue. Please check out In the ASIC-age, is it worth starting mining Bitcoin at home? for a more comprehensive overview of the mining situation.

Shares are simpler portions of work at a lower difficulty than blocks. They are used by mining pools to gauge the contribution of miners. You apparently found a single share, but it was found after the pool had started working on a new block. When your guiminer told the pool about it, it was already outdated.