Build targeted audience

Is there a guide on how to built targeted audience for an instagram account.
I'm managing some apartments for rental and I'd like to maximaze the reservations and advertizing them.
It's my first try with social media and I'd appreciate any help.

First you need a camera that you will use to Snap the apartments, then create an Account on “Rental Apartment" Niche. They will have some couple of hashtags for it, post some pictures you have snaped. Remember you should run it on a business account, promote the pictures you wish to. I guess this can take you a long way.

Is there any app paid or free that will help me with all that?