I am trying to replace a kitchen faucet but the water shut-off valves or the supply shutoff valves under the sink just won't budge. I tried spraying some WD40 on there to loosen them up but nothing. I am not a handy man at all and this is the first time I am trying to attempt something myself. So please elaborate for me.

Shut the water off at your hot water heater to by-pass those valves. They shouldn't be that hard to turn, might want to replace them.

The valve should not be that hard to turn. Are you turning the correct direction. They turn off by turning clockwise. Try a pair of pliers if it is that difficult. If you can't get them to turn off, turn off the water to the house and (assuming you have copper pipes) cut the pipe just below the valve. Replace with new compression fitting stop valves. Turning off the water at the water heater will only turn off the hot water. Come back if you further assistance, however you should post on the plumbing site.

Thank you for the suggestion hkstroud, first time here and was kind of frustrated with trying to loosen up the valves and so didn't look around the site to see where would be the best place to post a question. Thanks again though.

You are welcome, and welcome to the site and the world of DIY. I saw your post on the plumbing site. Take Marks suggestion and call the city for water turn off. Its no big deal for them, they have employees that do that all day long. As you progress in the world of do-it -yourself come back often. I think you will find a lot of people here who will do everything they to help.