plug in your adsl router into the wall
plug one computer into the router
open a webpage and type either 192.168.0.1 // 10.1.1.1
refer to your routers manual for username and password
eg: admin /password
setup your router to use dhcp
configure the computer connected to use dhcp
a restart maybe required depending on your OS.
open a browser and see if your connected to the net, if not go back and look at your routers setup again through the browser.
plugging in the next computer should be very simple and straight forward akin to the first one.
this information can easily be found on the internet from noobed full glossy images to text based sets.
always refer to your routers booklet before looking elsewhere for common usage problems, check the manufacturers website for updates etc..
If no-one gives your an answer to a question you have asked, consider:- Is your question clear.- Did you ask nicely.- Are you showing any effort to solve the problem yourself 
