Help adding custom image to follower alert

Hey!

I am having trouble adding a custom image to my follower alert on nightdev. Everything seems to work until I test out the alert, and the image does not pop up.

I’m wondering if some one could walk me through step by step, as I am not very tech savy.

Here is the image link for consultation
http://imgur.com/xjaAEVh

Thanks for any help you can offer!

Isaac

As stated on the upload form, the max size is 580x110 pixels. Your image is far outside this boundary.