1. Turn the pump off.
2. Make sure the backwash hose is attached, then unroll it (assuming you have a flexible backwash hose).
3. Set valve(s) to backwash and turn the pump on and let it run for a couple of minutes.
4. Turn the pump off. Set valve(s) to rinse. Turn the pump on and let it run for about 30 seconds.
5. Turn the pump off, then set valve(s) to "filter". Turn the pump on.
6. Add DE through the skimmer (how much to add depends on the size of the filter)
I would suggest going through the "backwash / rinse " cycle at least 2, if not 3, times before returning to "filter". You will be surprised how much gunk comes through on the 2nd and 3rd cycles. Just make sure you "rinse" before going back to filter - this clears out the valve itself and keeps the DE and backwashed crud from ruining your spider gasket.
Also, when you add DE, add about 75% or so of a full charge - no the full amount that your filter calls for. This info is in your filter manual somewhere, but it is normally buried. Some of the DE stays in the filter no matter how well you backwash, if you continually recharge with the full amount, the filter will gradually clog up.
I add DE by filling a bucket about halfway, then adding half of my DE to the bucket, stir well and then pour into the skimmer. Add more water and pour in until the bucket is cleared. Then do it again with the 2nd amount of DE. If you just add the dry DE directly to the skimmer, quite a bit of it will go directly to the filter as "chunks" of dry DE and never do anything useful (I know this because I have cleaned out my filter when closing and I used to add DE this way).