OK So we covered our back patio and now the drainage is messed up. Water collects under edge. What should I do?

We covered our back patio with a cheap and hasitly constructed "roof" and some corrugated fibergl. We did not think we were messing up the balance of the universe - but now water drains off it and cascades into the back yard, collecting against the back of the house! It is too flimsy for a rain gutter. Any ideas?