How to make images mobile & desktop friendly

Is there anyone who can help me with how to make my images on my website to be mobile and desktop friendly. This is to say, if access my website on a desk top computer the images must appear 100%, but when I access the website on a mobile phone the images must adjust to the size of the screen of the mobile phone or iPad being used

They are if your are using a Responsive template like EVO..

I am using EVO template but the images on my website are not adjusting to neither Mobile or iPad or Tablet screens, but on the Desktop computer and Laptop computer they appear normal.

This is why in need some help to get this images adjusting on Mobile, iPad and tablets screens

Unless you're running an app which may be different, this is what people will probably see:

1. Ipad

2. Phone

Maybe a screenshot of what you're seeing will help.