You have to do some more researching before you decide to just mess with claybarring. You could end up doing more harm than good and causing more imperfections in your paint.
When you claybar your car, you're helping to remove a lot of the surface debri and all the small particles that has lodged into your paint, etc. over the years. To be technical, you're "grinding' it off, I guess. It's the equivalent of using a polishing compound. It's easier, but not necessarily better. Not quite a replacement either. It can also be used to remove overspray, sap from trees that sprinkle all over your car, and can be used to clean the windshield and car windows, as well. If you try Google, I'm sure you'll find people who have found more purposes for it. Those are the main reasons I have ever claybarred a car.
Run your hand over your car's paint now (especially the hood). All those little bumps you feel will be gone. Claybarring makes your paint feel smooth as hell again. Kind of like an extraction. It seriously feels like glass afterwards, if done correctly. Lubrication is key, though! Before you claybar your car, you need to wash it to remove the loose crap.
Follow the instructions that come with your clay kit. A lubrication is usually provided. If not, you should get it. If you decide to be cheap, you can opt for a bucket of soapy water. Whatever method you choose, the surface you're running the clay over MUST ALWAYS be lubricated to avoid ruining your paint. Try working on small areas at a time. Knead your clay and run it back and forth over the area that's lubricated. Don't use heavy pressure -- use light/moderate pressure. Light until you really get the hang of it. Better safe than sorry, IMO. Check your clay often. When it's dirty, you need to knead the contaminated part into the center (like a ball) and flatten it out again. The box will probably tell you, but if it hits the floor, toss it out. It's no good anymore. Maybe only for your windows then.
You'll have to keep running your fingers over the area you're working on to feel out spots you might have missed. Depending on how bad your paint is, you'll definitely be able to feel a difference.
Wash > Clay > Wax > Seal
^ The general steps..
