To bend the knee, select the foot and move that upwards. Since the figures are IK-chained, you'll need to select the bone that's at the end of the IK-chain. If you move that part the rest will move too. Once you've got your rough positioning, you can fine tune every other part (like shin, tigh and so) through the parameter dials. Do this through the last 3 dials of transform, twist & side-side & bend. If you don't see the parameter dials menu, selct it through the window menu.

Artwork and 3DToons items, create the perfect place for you toon and other figures!

http://www.renderosity.com/mod/bcs/index.php?vendor=23722

Due to the childish TOS changes, I'm not allowed to link to my other products outside of Rendo anymore :(

Food for thought.....
https://www.youtube.com/watch?v=pYZw0dfLmLk