It's pretty easy to replace a faucet, but you probably don't have to. If the faucet is old, you might have what are called seats. If it is newer, you may have cartridges. If you know the brand and style, you can go to a plumbing supply and they will be able to fix you up. If it's not a high dollar faucet, they are easy to just replace. You look under the sink and turn the cutoffs off. you them disconnect the flexible hoses by unscrewing them at the faucet. They might need a little help, but probably aren't much more than hand tight. There will then be a nut on each threaded fitting that you disconnect the flexible connectors from. You can probably get them loose with a pair of channel locks. Faucet comes out, you clean up the sink or countertop, lay down some sealant and reverse the procedure.