Welcome to TFP.
Your primary concern is going to be keeping chlorine in the pool to avoid algae. The easiest way is with bleach. Next you need to get CYA in the water to protect the chlorine from the sun.
Your pool is between 5000 and 6000 gallons. Adding a 182oz jug of 6% bleach will raise your chlorine level by about 10ppm. I'd go ahead and add a jug by slowly pouring it around the edge. You need to get on this fairly quickly so you can stay ahead of the algae. It may require more chlorine several times a day until you can get the CYA dissolved, which may take a week. After that, you should be able to add a little every evening to maintain your chlorine level.
Once you get the first jug of bleach in there, get about 2lbs of CYA from Walmart and put it in an old sock hung over the side of the pool where the return enters. It will take several days to dissolve, and up to a week to become fully effective.
Once you get going, you'll need to be able to test your water. The primary tests are chlorine and pH. You can get by with the simple Walmart drop kit that runs about $20. You'll want to test both chlorine and pH everyday, and adjust as needed, most often that will be daily for the chlorine, and less often for pH. A better kit is available from TFTestkits.net, or you can buy a Taylor K-2006. These will perform many more tests than the cheaper kit, and can measure higher chlorine levels.
Run your pump 24/7 except when swimming, and clean/change the filter as needed.
Spend some time reading
Pool School Here are direct links to articles that will be particularly useful to you.
Temporary Pool Guide
Recommended Pool Chemicals
Test Kit Comparison
Recommended Levels
Your pool probably has a marginal filter and pump, so try to avoid adding powered chemicals.