How can we add or get a new gym in my town?

You need a level 10 ingress player to submit portals unless you live in an area where the beta test for pokestop submissions is online. Regardless, the suggestions need to get accepted by peer review from L12+ Ingress players and after that there are certain rules concerning S2 map cells which govern how new gyms are born.

As a continuation of Housunkannatin's answer, play Ingress. Before you do that, get a look at the intel server, and see who has resonators on the portals in your area. Try to figure out who these people are in RL, and get to know them. Try to be on the same team in Ingress as they are, so they are more inclined to help you. New portals become pokestops, and if you get 2 portals in a S2 level 14 cell, one of them becomes a gym. 6 portals gets another gym, and 20 gets a third.

Good luck. It can be challenging to find people, as Ingress doesn't have quite the social aspect that PoGO does. I finally made contact with Ingress players in my area, and we're growing the Pokestops and Gyms on campus.