You hit the button to cycle between your hideouts (Z, I think?) and then when you find one you want, you should see "I - Invest in Location" or something, so you hit I and it gives you a bunch of options. You can set up business fronts and stuff to increase the secrecy levels, as well as install cameras which allows you to see where enemies are during a siege, and you can set up a printing press which allows you to set up the Liberal Guardian. The Guardian has more effect than regular writing to newspaper (there's an option for it near regular writing), and raises Writing skill faster. It also lets you run the special edition at the start of the month. Just be careful about writing for it when there's Conservative free speech laws, as the location with the printing press may get raided.