How can I approve or reject a file?

Files can be approved or rejected in three ways:

From Browse or search results:

Click the green tick or red cross beneath the file.

From Media View:
 
Check the Approve or Reject button and click the Save button.

From the collection:

After adding the files to the collection, click the Batch Keyword Apply tab on the left and check the Approve or Reject button. Then click 'Apply Keywords'.