How do I make a dry creek bed for the run off water from the roof?

What about using a rain barrel, which would give you water for your yard when you need it?

Decide where you want your dry creek bed to go. Using a soft garden hose really works well to outline your creek bed and give you nice soft curves to the design. Then you will have to dig out about 12" so you will have room for rocks. All sizes of rock to line your new creek bed. Add a few plants along the top edge and you're all done. Don't forget to post a picture of your finished project.

As Harrow said. you might also want to consider placing a plastic drain tile. Its like a 6 inch diameter hose that will also help lead the water away from the house

Dig and slope your dry bed away from your home's foundation. Line it with plastic, lay river rock randomly, border the bed with larger rock, boulders or flagstone. You can add a walk bridge over the dry bed for purpose or decoration and plant several 'fountain grass' within the bed for curb appeal. You could also hang rain chains from your roof for added function and appeal. Have fun but don't work too hard. Best of luck.

Buy or make a rain chain which can lead to either a rain barrel or some sort of diversion on the ground to disburse the water to avoid flooding and pooling. I would make a dry creek bed with rocks that leads away from the foundation of your house.