ACSI sites, what is the actual process on arrival?

I will be using my ACSI card at the very first site we arrive at in France and will also use it in Spain, sometimes for just one night and probably up to 2 weeks at a time.

Would anyone kindly give me a step by step guide of the process that I need to follow, whether it be just the one night or more. I would rather know in advance what to expect then I can recognise if anything appears to different. Is it different in France to Spain?

Regards, Roy