Creating a new file
To create a new file, simple tap on the large circular orange button located in the bottom right corner of the Gallery. Valence 3D has its own file format (identified by the .valence extension). The valence file format is optimized for fast loading and saving.
Gallery View
Importing an existing 3D file
The other way to create a new file within Valence 3D is to share a compatible 3D file (OBJ, STL, USD, USDZ) to Valence 3D from the Files app on iOS. Once you've selected a file and shared it with Valence 3D. Valence will create a new file and open it. Then you'll be greeted with import options (units, etc).
If you share a 3D file with Valence 3D while you already have a valence file open (i.e. you are in the Modeler View) then the shared 3D file will be imported into active valence file's scene. Then you'll be greeted with import options (units, etc) as usual.