BBB is so simple, really...but there is alot of information to absorb and it can overwhelm you at first. Just take your time and read the relevant articles several times. It will sink in.
The shock bags - what was the ingredient? Was it Calcium Hypochlorite or was it Dichlor?
You need CYA in the water, Dichlor has CYA but Cal-Hypo doesn't.
You can use 8 oz of Dichlor for 5 days to build your CYA level to the recommended range, and then start using bleach. Each night you will need to test your chlorine levels and add bleach, and I guestimate you will probably need to use a little over 2 cups of bleach each night - maybe a little more, maybe a little less.
I would recommend you pick up a small test kit, like the HTH 6-way sold by Walmart for around $20.
Hope this helps, post back if you still have questions.