Step 1
Start a new post in the "Advanced" mode. You need it "Advanced" to be able to add attachments.



Step 2
Click "Manage attachments."



Step 3
Browse for the attachment.



Step 4
Upload the attachment.



Step 5
After uploading, the attachments appear in a list as shown.
Click or tap an attachment, it will open in another tab.

Note: Only 5 attachments can be used in each post. If you have more, you will need to split it into several posts.