If your resume and cover letter are stored in a different folder, click on the appropriate folder.
Click to select the file you want to add to your email message, click on Insert to attach the document to your email message.
Before you click Send, send the message to yourself to be sure all the attachments come through and your email message is perfect.
Send a copy of the message to yourself, as well as to the company, so you have a copy for your records. Add yourself as a Bcc (blind carbon copy) by clicking Bcc... and adding your email address.
Then click Send and your cover letter and resume will be on the way to employer.