The Uploads tab provides a way to attach files to the current task. This dialog is also used to delete existing attachments. Which of these actions you can perform depends on your privileges. 

To upload a file attachment, specify the path to the file you want to attach using the Attachment Name field, or click the Browse button and find the file using the Open File dialog. Then press the Upload button. To download the uploaded file just select the link from the uploads list. If you want to delete an attachment, click the Delete button.