To insert an image into an email,

Select the insertion location for the image by moving the mouse cursor within the email body and clicking were you want the image to appear.  Some templates have defined image area such as for a logo but you may put an image anywhere within the email body.

Select  on the email editor tool bar. The image manager opens in which you can either choose an existing image from the list to the left or, selecting the add image button to upload a new image into your account.

From the Insert/edit image library, select the image from list. The selected image appears in the preview box on the right. Select the Insert button and your image will be inserted into the place were your cursor appears in the editor.

If the desired image has not been uploaded to the image library, select the Add Image button and browse for the desired image on your computer that you want to upload, then select Upload.

Once you have selected an image, select Insert. Your selected image appears in your email.