You know the signs of a backed up toilet: the toilet bowl is overflowing and the rest of the family runs for cover.
Your natural inclination, understandably, when it comes to plumbing repair is probably to get as far away as possible from the germs and gunk, and then call a plumber to schedule an (expensive) emergency visit.
Be brave: You can usually handle a backed up toilet yourself.
The first step to keep a bad situation from getting worse is to remove the top of the tank. Flip the rubber stopper in the bottom of the tank back over the drain hole. This will stop the flow of water into the bowl.
Apply a thin ring of petroleum jelly around the rim of the rubber cup of a toilet plunger. This provides for a tighter seal against the bowl - and improves the effectiveness of your pumping action. Now place the plunger cup snugly over the bowl's drain opening.
Give it a few vigorous pumps. The idea is to force the obstruction causing a backed up toilet beyond a U-shaped section of toilet pipe (called the 'trap'), and into the drainpipe. The blockage should then flow away, and take with it any backed up water.
If your efforts don't stop the rising tide, the problem may lie elsewhere in the drainage system. Now that you've ruled out a simple clog, it's time to call in that emergency plumber.
While you wait:
Visit the Clean Organized Home Store for the products and supplies you need to fix a backed up toilet - and to help prevent future plumbing problems.