You want the user of this model to be able to specify the following inputs: Input Vegetation and Input Proposed Roads, as both of these could change over time. You also want the user to be able to set the path and name for the Output Habitat Locations output and the final output, Output Impacted Habitat. So the user can specify values for these parameters, you’ll make them model parameters.

Right-click the element Output Impacted Habitat and click Model Parameter.
Right-click the element Output Habitat Locations and click Model Parameter.
Right-click the element Input Vegetation and click Model Parameter.
Right-click the element Input Proposed Roads and click Model Parameter.

Click Model and Save, then click Model and click Close.