There are two ways to add an attachment to a page:
In this way, you need to open the Attachment pane of the page.
1. Click the Upload New File in the attachment list pane. The upload window will appear.
2. Select a file from your local device, then click Open. The file will be uploaded automatically then.
You can use this method when editing the page content by WYSIWYG editor (Rich Text editor).
1. Select a page to which you want to add an attachment.
2. Select Edit at the Page Control area. For more details, see the Edit a page section.
3. Select the Rich Text editor on the page toolbar.
4. Click 
on the toolbar of the Rich Text editor, then select Attached File... from the drop-down menu.
The Link form is displayed as below.
5. Select a file to upload. Now you can upload a new file or select one file from existing files.
Upload a new file:
i. Double-click Upload new file, or click Upload new file --> Select in the Current page or All pages tab.
ii. Click Browse to select a file from your local device, then select Upload.
Select from existing files: Click the file, then select Select.
The form to edit the link parameters appears.
6. Provide the link label and tooltip.
7. Click Create Link to update the link.