Highlight the text that you want to link, and click the Insert link button. Copy and paste your link into the pop up box, and choose whether you want to the link to open in a new window. Then click Insert link.
Click on the Insert image button. Copy and paste a link to the image into the pop up box, and click Insert image.
Scroll to the bottom of the bulk message page, and click on the + Add File button. Then click on the Browse button. Select your file, and click Open. You can attach multiple files to one message. If you would like to remove a file, click on the red trash can icon to the right of the file.