Change last names into numbers, which relate and display images

Im new to JavaScript and don't have the knowledge to write this myself yet. Any help would be great.

I'm creating pseudorandom illustration generator, comprised of 3 images. They'd be chosen by their name and displayed. Live update would be the best.

I'd like to have the user enter their last name (into a field) which will be changed into an individual set of 3 numbers. From those numbers I'd like the images to be chosen, the 1st from the first etc. then display them vertically respectively.

Any input is welcome, I'm sure there's an easier way of doing it. Thanks for your time.