You want to stretch all of your leg muscles (hamstrings, quads and calfs) and then probably your pecs, due to the arm position. You might be best investing in a stretching book.

Glad your feeling less achy. Obviously you just increased the stress on the muscles too quickly and the ache was them unable to cope. Now they are getting used to it and getting stronger the ache should die down. As I said before, just watch how quickly you increased your milage in the future,