Customize page won't load

I installed WP 2 days ago and despite multiple attempts and using different browsers, I have yet to be able to customize the theme that I have activated. When I select “customize” the side bar comes up and the loading icon but nothing further happens, same thing happens with the “live preview” button. I am very green to all of this so the coding and troubleshooting are all greek to me, which I do not speak if you were curious! Thanks so much for your help.