1. Open a file in Mariner Calc or Calc Lite for iPhone or iPad. 

2. Tap the file menu button, then tap, "Open In..." 

A menu of apps that support the file appear, including "Open in Box". 

3. Tap on the Box app icon. 
The Box.app launches and an Upload screen appears.

4. Choose a destination folder, then, tap on the "Upload" button. 

A progress indicator shows the upload progress. Once it displays "Upload Complete" the file is now available in your box account.