Step 1: Buy a brain. This can be done at God's Body Parts, Etc. for a mere $9.95.
Step 2: Install your new brain. You can either read the instructions that come with your brain and do it yourself, or for an extra $19.95 God will do it for you.
Step 3: Turn on the switch, which is located on the back of your head. Just wave your hand around in back of your head. If you can't find it, try your other hand. You're obviously missing that one.
Step 4: Decide what to think about. This one's up to you. The choices are unlimited!
Step 5: Think about it.
Note: If for some reason you have trouble with Step 5, return to God's Body Parts, Etc. and exchange your brain for a working model. If you DON'T have trouble with Step 5, then you shouldn't be reading this, so exchange it anyway since it must not be working right.