Press the "•••" icon on your file to get to the options menu.
In the options menu, you can select to have the file available offline by pressing the device icon on right side of sync status.
Once this is pressed, the file will start to be downloaded on your device.
By switching the setting off again, the download is cancelled.
A green overlay icon is present if the file is available offline..
For the file, you have the following options:
1. "Delete" will delete the file.
2. "Rename" will allow you to rename the file.
3. "Create link" will create a public link to file, so you can share it with others.
4. "Open with" will allow you to open the file in another application on your device.
5. "Cancel" will bring you back to the previous screen.