Today I was unfortunate enough to find that every time I flush a toilet inside my house it backs up into an outside pipe. I went to check and found an awful mess and a flooded pipe. I am not sure where the problem actually is and what to do. Any suggestions or diagnosis? Thanks!

What is the outside pipe... a cleanout? If so, then the main drain line itself is clogged, and all plumbing fixtures in your home are contributing to the backup at this point.

The main drain line will need to be snaked to clear the drain, OR, if you are on a septic tank the tank may need to be pumped?

If you suspect the main drain and are on city/town/county/etc. sewer then it may benefit you to call your local public works department... they may snake the drain line free if you are lucky! Otherwise, you are calling a plumber or renting a sewer drain cleaning machine and gettin' busy (available at all home depot tool rental centers)!

YouTube (http://www.youtube.com) will have plenty of videos on snaking a main drain line.

Here's a video of a guy using a manual drive sewer machine (they have power feed machines, too):

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Mark