You can edit any created template.
To do that, choose the Templates folder on the left-side menu and open the email template you wish to edit.
Enter the text of the message, add a signature, smileys, images or links, and attach documents. You can also mark the template as important or request notification. As soon as the message is composed click the Save template button to save it, since templates are not autosaved like drafts.
If you leave the Templates folder without saving you will be prompted to save: click the Save / Do not save button or Cancel to continue editing.
The same way that you manage your emails, you can delete a template, move it to another folder or add tags.