No worries. In FloXpress you do need to make sure your entire "computational domain" is enclosed. There is a lid feature but that only works well with planer geometry. If you have a complicated hole, you may need to make a custom plug to fill that hole.
Also keep in mind that a hole is not filled if your lids only meet at edges. A lid is only valid with overlapping volumes or touching faces.
This can be a frustrating task to complete if you have complicated geometry which is why I suggest simplifying the model if possible.
All the best,
what do you want to do in this analysis? even if you fix the lids, if you want to see how the water comes out of the showerhead, that isn;t something even full flow simulation can do.