Insert picture/image gallery?

I searched to see if there was anything for this, but I couldn’t find an answer. Sorry I’m a greenhorn and still getting my legs.

I’m looking to make it so that the job posting user can upload an image into their job posting. I’m using job manager so customers can post listings looking for a freelancer to make them custom items.

Is there a way I can do this without completely changing my theme? A plug-in? I didn’t see it as an option in the purchasable plug-ins.

Thanks guys!