Can't change product image sizes

Hello,

I would like to make the images of products larger. But when I do all the steps as explained in tutorials, nothing changes. I did this:

Woocommerce –> Settings –> Products –> Display
Then I changed the sizes.
Then I regenerated the thumbnails.

But when I go back to the shop page, nothing has changed! Now, I read online that I might have to change something in the CSS file. But I don’t know how to work with CSS. First of all, where do I find the Woocommerce CSS file?

Irene

https://wordpress.org/plugins/woocommerce/