Some mail clients will allow you to create it as an attachment that created each time a message is sent, but the most common way would be to simply use an HTML tag which would look like the following:
As far as the path that you will use, it depends on where you upload the image. For ease of access, you could upload it to our public_html directory using the cPanel File Manager in which it would then be located at http://example.com/imagefilename.jpg
<img src="http://example.com/pathtoyourimage.jpg">
As far as the path that you will use, it depends on where you upload the image. For ease of access, you could upload it to our public_html directory using the cPanel File Manager in which it would then be located at http://example.com/imagefilename.jpg