You can add up to three attachments to the message being composed without having to go into the 'Attach Many' screen. If you need to add more than 3 attachments, you can click the 'Attach Many' button which will take you to another screen which allows you to add as many attachments as you want. If you only want to add 3 or less attachments, you do not need to click any other buttons to explicitly attach the files. You just need to select the attachments, and click Send when you are ready.
You can add files from your File Storage area to your messages as attachments. Click on the 'File Space' button, which will take you to the File Storage screen. Here you can select the checkbox(es) of the files you want to attach, and click the 'Attach' button. The selected files will appear in an attachment list at the top of the screen. You can add as many attachments as you like (up to a maximum of 7M). When you are finished adding attachments, click on the 'Done' button to return to the Compose screen.