If you need stabilizer, and have access to a Sams Club, buy their 24lb pack of 1# bags of 100% dichlor shock. Each bag will add about 7 ppm of chlorine, and about 6 ppm of stabilizer, per 10K gallons of water. Otherwise, order dichlor from Amazon:
Kem-Tek Dichlor 22 lbs
We do NOT recommend buying dichlor locally, otherwise, at least until you are an EXPERT reader of chemical labels. The chlorinating pool chemicals sold at Walmart, Kmart, Costco, and most other local stores are diluted blends, sometimes with copper and other products with bad side-effects.

You can also add stabilizer directly, but it doesn't dissolve quickly, and people often have to clean their filter before it dissolves. So, if you buy stabilizer directly it might be better to use the sock trick: put the stabilizer in an old long athletic sock, and hang it in front of a pool return.

On your pool, with an SWCG, to reach a CYA of 70 ppm, you'll need 6# of stabilizer, or ~ 13 lbs of dichlor.