Can you help me decipher my filter and how to use it?

[taurusnyy]

OK so I have determined that I have a cartridge filter and now want to figure out a few things I am going to insert a pitcure to assist in my questions, any help is appreciated.
I have an oval ABG pool 12x20


How do I backwash my filter? and what does this do?

I would like to get a pool vacumn but am confused as to how to attach it?
- based on my pitcure from what I am assuming the vacumn comes with two hoses one to put in the skimmer ( does this mean to literally shove it in the skimmer?) then the other hose from pool return line that goes into pool? my pool return line connects to my pools light which pushes out filtered water - so am I just unscrewing the pool hose from the the light fixture and connecting it to the other hose for the vacumn?

Drain valve? I have it plugged in and do not have the drain valve- what is this used for- I have read of people having waste lines- is that what this is? Is it necessary to get the optional outlet valve?

I hope someone can clear this up- they installed my pool when I was not there and I could not ask them questions.

Thanks in advance.[/img]