Can I get internet on my desktop from a router??

Yes

If you are not capable of doing this, Contact your PC shop/service provider for help

Actually, that depends. Do you have high speed internet, and a network card in your desktop? If so, you just plug the high speed internet connection into the 'WAN' or 'Internet' port on the router, and then one of the other ports on the router (usually numbered, go with 1 or 2), put a cable in there, connect the other end to the network card on your computer.

If you bought a router then it came with instructions specific for that router.