...
Press the + button on the top right side of the screen to bring up the add required attribute screen.
...
Select the resource that you want to require the attribute to match; your choices are Carrier, Driver, Trucks and Trailers. The second drop down field options are must have and must not have. The third dropdown option is the attribute that you can chose. Note that the attributes that appear in the dropdown field will change depending on the resource type that you choose from the first dropdown. The final dropdown field allows you to select a commodity. If this is a blanket attribute you can assign it to all the commodities. When you are done, you can press Add Attribute and your attribute will be created.