It’s great that many home- and building owners these days want to hone their DIY skills and make many repairs on their own. However, electricity is no joking matter, and amateurs should leave in-the-wall electrical work to their professional local electrician — at least until they get in the necessary practice.
If you do want to be able to make standard electrical repairs on your own, begin with projects that are outside of your wall. Try rewiring an outlet that isn’t yet installed, or wire your own lamp. Once you feel comfortable with doing out-of-the-wall electrical projects, move onto those in the wall, but be sure to cut the power first.
Be sure to check with your local building department before making any permanent electrical fixes, as many city ordinances require all electrical work to be done by a certified electrician. And, when in doubt, call in the professionals. It’s always better to be safe than sorry.