Start researching your local ordinances and bylaws. Like someone mentioned here, there might be a reason your town dies after 2200.
Think about the kind of things you want to see in terms of nightlife. Does that mean live music? Block parties? Techno night at the clurb? Kink stuff (seriously)? Theatrical performances? Hash and coffee socials (sort of a joke, but thinking through the logistics of such a thing has been my daydream du jour recently)? Etc.
Find others who would be interested in the kind of stuff you’d like for nightlife activities. Start talking $ and logistics - are there any grants you could try and apply for? Fundraising activities? Where are you going to do this stuff? What do you need in terms of insurance? Do you need to address any pesky bylaws, and can start working with your local government to try and tackle that? And so on.
Make a plan and act.
The big starting point is really just defining one or two things you want to see, and working to get to the point where you see them. In the course of this you might be surprised by what you find (someone mentioned good ol’ Ottawa, ON as an image of the place you’re describing - but there’s actually a decent amount of stuff, both above- and underground, you can find when you start poking around).