You can add files to a bug/feature you created. Click on the bug/feature you created and under the Files tab. Click upload file and choose the desired location of the file in your computer then click open. Supported files  pdf, doc, docx,xls,xlsx,ppt,potx,pptx,rtf,txt.  Each bug/feature is allowed to store a maximum of 3 files with a maximum size of 3mb each.