Is it ok that it looks like that after I roasted with no oil (first use)? I tried to rub it off really good it with a soft tissue and a dish soap. Except whatever left on the surface (what you see on the photo) food wasn't sticking to it.
No, I don't believe so... it looks more like cooking residue to me. But you should be able to clean it sufficiently with one of the tricks below.
One trick, which I've used for any type of pan, is to put a small amount of water in it, then heat the water to the boiling point and let it cool. It softens up anything left on the surface, making cleaning much easier.
Another thing I do on a regular basis is using one of two products: Barkeeper's Friend, or Bon Ami. Similar to baking soda [mentioned on the WikiHow page: How to Clean Ceramic Pans]. All three are gentle, slightly abrasive cleansers that should not damage your pan surfaces.