slack adjuster

I want to buy a car, but I think I need to think about this, because I see my friends if their cars have what problem, they don’t know what to do, they have to buy their own slack adjuster, if the parts are what loose, he you can use slack adjuster fixed good, I think this is good, but my own ability is not up to much, so I think if I have slack adjuster, I will not do good, a very important reason for this is I still hesitate, I now do not know how to do it, but I still want to do, because it was myself to face.