If you are trying to upload a file such as an image into a contact's record - within the Files section you will need to click on the following:
Upload
Add Files (as shown below)
This will take you into your documents - you will need to select where on your iPad you want to get the file from - it could be you have to 'browse' your images
When you have selected the image to upload select 'Done' On a PC this may be 'Open'.
You will then see you need to select 'Upload' for the file to be added - when the file is at 100% the upload has completed.
