Do you have wireless now, that your pc uses? If you do then that wireless signal comes from your wireless router. A lot of people have a wireless router and don't actually realise it is wireless because they have it connected to their computer with a cable (As do I, though i do in fact have both wired and wireless off it).
When you set up your wireless, you have the option of setting a password, WHICH YOU ABSOLUTELY SHOULD DO!!!!, but many people do not. if you don't you effectively give your neighbours and anyone else close by free access to your system, and if they chose to download anything illegal, it will trace back to your IP address.
If you have done all this at some point, but have forgotten your password, there is usually an option to reset the entire router and start again. Dig out or download the setup instructions before you try this though (unless you're tech savvy).
You usually set up your wireless router by opening Internet Explorer (or whatever browser you have), and then typing into the address bar 192.168.11
You type this exactly where you would normally see the url, eg
Google but you don't need anything at all except the 192.168.11.1
You put this in and hit enter and then you will usually be prompted for a username and password - This can be different for different routers, but for the Buffalo router as an example the username is ROOT and then password will be blank if you haven't set one or whatever you have chosen if you have set it up before. Once you have done this you are in the setup screens and you will have a multitude of options including passwords. Once you have set this, then that is what you put in if you try to connect with your phone. World of difference to 3G
You only have to do it once, and it will then remember the connection and simply connect automatically when you are in range.