I'm a home maker who has done this many times but in no way am a proffessional. It would be easier to talk you through this or come help you. but == here goes. The first thing to do when water isn't coming out of the tap very well is to check the screen on the end of the spout and make sure it isn't clogged with lime, rust or other junk. If that is clear and you are sure it is your faucet -washer. Shut off the water. either under the sink or at the source. you will need a screw driver and an adjustable wrench. remove the handle and any other housing so you see the faucet mechenism. This is threaded. turn it out. On the bottom you will see an O-ring that is what needs to be replaced. Replace it. The harware store can help you there.Check for lime and other obstuctions. Then put every thing back together in the reverse order you took them out. Tip: When taking something apart lay it in order it comes off. or number items. It makes it much easier. Hope it works.
Mary
February 2009