I have no bitcoins at all. But how do I get them? Can I deposit money through my credit card and convert them to bitcoin currency or something? Also, say I have 10 BTC. Can I acquire that in physical money?
You can use buy BitCoins on exchange market like Mt.Gox.
You can get BitCoins by mining process. But this second option is very slow and hard. You can join some mining community to create blocks and get bitcoins for it. It takes couple of hours of your computer to make calculations worth 0.0001 bitcoins.
You can find quick intro here: How to Get Bitcoins.