This year I'm going to try Dichlor and use the technique in the pool schools beginners guide. The pool does have a plastic skimmer, should I put it in a sock and in the skimmer, or in the sock on the return?

Step 5 - the first four days
The first few days will be spent using dichlor to add chlorine while also raising your CYA level to help protect the chlorine from the degrading effects of sunlight. If you want to be able to jump into the pool as soon as it's full, use the Pool Calculator to determine the amount of bleach needed to raise your chlorine level to 6 ppm. Add that amount of bleach while the pump is running. Wait an hour to let it circulate before you use the pool.

The first four days, you will use dichlor to both chlorinate your pool and raise the level of CYA (chlorine stabilizer). The first evening, after you're finished swimming, turn the pump back on, test and make any adjustments to pH. Let the pump circulate any chemicals added to adjust pH (30 minutes or so) and then add one ounce of dichlor for every 500 gallons of water. To add the dichlor, add it first to a bucket of pool water and let it dissolve, and then dump that into your pool. Let the pump run overnight. This dichlor addition will raise the chlorine level to about 8 (assuming no chlorine was added prior . . . if it was, the chlorine level will be a little higher, which is fine), and the CYA level to 8.

Repeat the above procedure each evening for four nights total. At the end of four nights, your CYA level should be around 30, right where it should be. After four evenings of adding dichlor, STOP USING THE DICHLOR. This is really important, even if you have extra left over. There is a complex relationship between chlorine and CYA, and too much CYA is absolutely not a good thing.

Each evening, continue to test your pH and chlorine, and make adjustments as necessary to maintain both.