Please follow step by step instructions:
1) Kindly hover on M logo and click on Emails.
2) Hover the cursor to the Content Tab. It will display the existing contents.
3) In order to create a new content, hover over to the Contents Tab again and click on New Content.
4) You can use the existing content in a template by clicking on the drop down arrow button, I am attaching a screenshot for the same:
There are two situations in which you can edit an existing template:
a) In case you have created the template.
b) In case you have been added as "Editor" before saving the campaign.
While sending the campaign we require content and if you wish to use a template that can be used only under Content because the template is a part of the Content and further Content is a part of the Campaign.
An automated tag will be created for the template created and we can use that tag to a maximum of two different templates.
Note: The tag name must only contain lowercase alphabets, numbers or underscores.