Micra k11 Service and air conditioning

Hi all,

Im fairly new to this, I have a 3 door 2001 nissan micra k11 with 60k miles on it. Body work is a bit beat up cus its my first car but I want to perform a service on it and do what I can to make it run as well as possible.
I also need to fix the air con, it always blows warm air and not cool air and I need to fix this now its summer.

Any Advice would be greatly appreciated.
Many Thanks