How am I to do this if don't have a mouse ?

My mouse was not working it turned on but only was good clicking no scrolling, so I went to iShop

and there I was told that I needed a new 1 because the "light thing" for scrolling had died, so I bought

a new 1, but now I have now idea how to pair it with the computer. The mouse turns on but no message

in screen saying its connected. I don't know how to use keyboard "shortcuts" either, I found a page with

a list of shortcuts but I did not found 1 that would help me. Please help!