Hi and welcome
What kind of pool is it? Is it a temporary pool, like Intex Easy Set? If so, there is an article in Pool School that you should read for advice.
How many gallons is it? 15 x 24, oval? or is it 15' round and 24 the height?
See if Kmart has some metal sequesterant, it sounds like the water has iron...the water will turn funny colors when you add chlorine. Sequesterant will help prevent staining.
Do you have an Ace Hardware, Lowes or similar store that might have pool supplies?
You will need a test kit, so order one of these recommended kits online:
http://www.troublefreepool.com/pool-school/pool_test_kit_comparison
This article compares the two kits we recommend.
You don't need to shock necessarily but you do need to add chlorine, in the form of clorox/generic brand bleach - 6%. Look for sodium hypochlorite 6% on the active ingredients. (No scents, etc. make sure it's just 6% bleach).
You'll also need stabilizer/CYA - if Kmart doesn't have it separately, see if they have Dichlor granular chlorine in one pound bags. Dichlor (look for dichloro-s-triazinetrione) has CYA in it, so you can use it to chlorinate and raise your CYA at the same time. Otherwise you'll need to order stabilizer online. Stabilizer protects your chlorine from the sun, otherwise you won't be able to maintain chlorine in your pool.
Learn how to use the Pool Calculator - instructions are in Pool School. It will tell you exactly how much of each product you need to add.
Without test results its impossible for us to know if you need to adjust the PH and TA. So order a kit ASAP - I highly recommend the TF100.
Read the articles in Pool School, after two or three read thrus it will start to make sense.
Hope this helps.