Hello, thanks for the quick reply.
I think you misunderstood me, it’s not about any sidebar but about the shopping cart sidebar. When I add any item to the cart, the “cart sidebar” appears, the background is slightly hidden and from there I can add the “cart”, immediately to the “checkout” or continue shopping.

I know that I can add a sidebar with widgets at
https://woodmart.xtemos.com/cart/

But it is about the floating AJAX shopping cart! (see screenshot “Screen1”)
This is for example in 95% of all demos preset it is about class="cart-widget-side woodmart-cart-opened".
This can be activated/deactivated under.
Theme Settings -> Shop -> “Action after add to cart” (look at screenshot “Screen2”)

Exactly this sidebar is not shown to me under “WordPress Dashboard -> Widgets”, so I can’t add HTML blocks there.

Now I’m looking for a way to insert my HTML block or an image there, as described above in the original post (please read through my first post again and look at the images for it, thanks!).

Best regrads.