Rear shock absorber - Monoshock Explanation

[txm123]

Hello ,this time I'm writing to know a bit about the functioning of a monoshock.
I broke the one that comes with my bike and I can{t be sure I{m undertanding how does it work.

It has a spring which is adjustable i guess more quicker or slowest response,it has a gas chamber which i can adjust turning a knob and it has another screw in the bottom which I{m not sure why is it there.

I noticed that inside the chromed tube that goes into the shock absorber there was a pencil like aluminium tube, I think this is kind of a flot that has something in common t}with the oil inside the shock? Am I right?

Please give me all the info you can so i can Be sure I'm understanding how does it works...

its similar to the one in the picture...


Thanks
Alejandro.