How to show images below a select box according to the value?
As far as I know there are no ready made solutions for this, and you will need to write a custom module. The way to do this would be to implement hook_form_alter to modify the select element and add a #ajax property. 

If you've never written a module with hook_form_alter then this article might be of help: very-introduction-drupals-hookformalter

And here are some relevant questions on Drupal answers: 


adding-ajax-to-existing-node-form
how-to-use-ajax-in-form-alter-in-drupal-7