Help with dynamic content

Hi, no matter how many times I read the documentation on dynamic elements in my theme I cannot figure it out. I admit, I am not a web developer, just a tinkerer who normally can figure this stuff out.

On our website we have a couple of testimonial carousels which load a random quote from a set of testimonials. I just want it to maintain this random load on each refresh or visit rather than be static if it was cached.

Anyone able to help or point me in the right direction?

The content is rendered via a get_ where the homepage pulls in another php file if that helps.

Many Thanks,