You need the parachute before you can do this which you unlock after finishing Yusuf's second mission. You only have to buy eone and the map will be updated with all base jump locations.
You do not need to 100% the jumps. There are several jump requirements:
Jump off 5 buildings and land on the bullseye.
5 jumps require you to land on a moving vehicle (4 trucks and 1 boat)
5 jumps will be from a helicopter, you need to go through the pink rings and land on the bullseye.
With a little trial and error you shouldn't have any issues with this.