Select the feature you would like to import attributes for and the feature details menu will appear, click on import attributes.
Click on the down arrow to see and be able to scroll down the list of available data, for which attributes can be imported.
Select the map layer that you want.
Now click on a feature on the map to import attributes
The map layer feature details will appear as a selectable list of attributes that you can import to your feature.
Scroll through the list, make your selection and select import selected attributes
These selected attributes will now display in the general tab for your feature.
You can import data from multiple map layers and can follow the same steps as above to import these.