Note that a gloss or semi-gloss will look slick and shiny and you might prefer a more flat matte finish.
You can paint with spray or brush.
A brush will look streaky in many cases.
For spray, you can get spray paint or use a separate sprayer.
You need to mask off the coping for spraying.
Don't allow paint to get in the track too much as that can interfere with the liner going in.
If the old liner is in place, that should give pretty good protection for the liner channel.
Some paint will do better with a primer, so see what the instructions say.