installing & connecting smush

Hi There,
Is there a tutorial anywhere to teach someone how to install and activate Smush pro? I was able to add the free plugin just fine but for some reason I can not figure out how to get the free trial of the pro version working. The instructions provided aren't clear to me. I read what to do the problem is knowing how to do it... any help would be greatly appreciated.

Also, can you tell me now small Smuch Pro can compress a 32MG image down to without compromising too much in quality?

Thank you,
Rachael