Connecting carpet to carpet

I have a built in desk in my bedroom and I am looking at removing it so I can put my chest of drawers there instead. When the house was built the desk was put it before the carpet was laid. We have spare carpet and I am told it is possible to join the two together (as when the desk will be removed there will only be concrete on the floor.) I don't have the exact measurements at the moment, but it is only a very small job. If you think you could help please get in touch.