You need to follow the rules for pool clean up--they are listed in one of the stickied posts in the various forums here.

Personally, I wouldn't bother with the DE right now--there is SO much material you need to clean out that you'll be backwashing excessively--when the pool is clean but not crystal clear, then use the DE to give your water that "polished" clarity.

1) You need to keep your FC at shock level--for CYA=40 that means 15 ppm.
2) You need to brush your pool floor and walls once a day. If you don't have a brush the Leslie's Whale brush is a really good one, but any brush will do. However, if you have a vinyl pool do not, Not, NOT use a metal wire brush. Brushing knocks the algae loose making it easier to vacuum out and filter out.
3) You need to vacuum to waste once a day--get that gunk out of there and you don't want to clog up the sand in your filter with it. As Watermom tells you, get as much of the leaves and other large organic mass out as you can.
4) Use my favorite ingredient: P.O.P.P.--that means Pool Owner Patience and Persistence!