On this page of the Mr Prepper guide, you will find information on how to obtain new blueprints.
In Mr Prepper, you can obtain new blueprints in two ways. The first is to use the Workbench to dismantle items you have in your home or inventory. Of course, not every object can be disassembled. In this way, you can learn the blueprint of almost every object in the house right from the beginning (when you dismantle something, you keep the materials necessary for crafting the same item). You should do this after obtaining new tools, such as an axe or pickaxe – you won't have to pay money for them ever again.
The second way is to develop the Workbench. It has 5 levels and each of them gives you several new blueprints for furniture and other objects useful for your house. A complete list of blueprints can be found on the Workbench blueprints - list page.