/diy/ - Do It Yourself

So I want to replace a old light outside my house door. It's currently hooked up and works however I want to replace it with a motion censored light. I want to move forward with this project but I honestly have no experience when it comes to electronics or replacing these types of things. Normally I'd have my farther do this sort of thing but he works alot of hours and just doesn't have time right now to do it.
I know when approching this sort of project you generally turn off the power to your house (or something along that level so you don't electrocute yourself). Can anyone give me any advice and tips? Is this generally a simple procedure?

Sup /diy/niosaurs, I know this is a slow board but I poorly planned a rush job to the local hardware emporium and I wanted to do some woodwork this week, any suggestions on some moderate level diy project I can make? Appreciate any quick responses thanks guys, my first diy thread, but long time lurker