As you probably have noticed you are able to build your own ranch, and put the buildings wherever you like.
New buildings will be added soon, allowing you to customize the features of the game.

The first new building added is the Tack Room.
Once you buy a tack room, you can go there by clicking on the image in your ranch.
A tack room allows you to store some of the tack you do not want to accidentally sell.
You can store the tack there and withdraw it later, when you want to tack your horses.