Many washing machine repairs can be done by a home opwner, savings hundreds of dollars. Whether the tub is not draining, or the clothes are not coming out clean, a service manual will help.
Of course, always unplug the washer before working on it, and have somebody help as they are heavy and can tip over.
Wikpedia (https://en.wikipedia.org/wiki/Home_repair) gives a nice write up on repairing washing machines as well, but it does not take the place of having the repair manual and the DIY repair manual. Refer to all these resources before starting your repair.
Always remember maintenance of your washing machine to prevent some repairs such as checking the hoses, not overloading the unit, etc.