Attaching New Page to Parent Tab

I actually have two questions / issues. 1) I have created and published a new page that is intended to be attached as a “child” to an existing tab. I have selected the “parent” tab but the connection is not made. The new page is found when I review the dashboard / pages, but it is not shown on the actual website. How is the parent /child connection made? 2) I have attempted to add a photo to the new page by selected the image that has been uploaded to the gallery. The photo is not evident on the new page. How to make that happen? Thx, Randy