In the existing UI, attachments are added to the request by clicking Attach Documents in the Attachments list on the Request page. 

In the NextGen UI for Concur Request, attachments are added to the request by clicking Attach Documents in the Attachments menu on the Expected Expenses page.

Clicking Attach Documents opens the Document Upload and Attach dialog. 
Click Upload and Attach to add an attachment to the request.

After adding an attachment to a request, the attachments icon, , is displayed next to the Attachments menu to indicate that the request has attachments.

You can view, delete, or add additional attachments from the Attachments menu.