You can specify coordinates for a location directly within the app as follows:
Firstly, on the locations screen, click '+' to add a new location:
By default, the new location will have the current primary pin coordinates (or secondary, if you specified secondary when prompted - you'll only be prompted if Geodetics is enabled), but you can edit the coordinates manually as shown:
You can also manually rename the location to something appropriate before saving the new location.
Alternative approach: KML Import
In addition to entering coordinates directly, you can also import KML files with Placemarks directly into the app: simply email the KML to your device, and choose Open in TPE for the KML attachment.