See this sticky thread:
https://jalbum.net/forum/ann.jspa?annID=205
ETA: The tool for converting extra pages won't work in your case, since you have created a custom page, with a different name. Delete and re-add
Om Stefan.htt.
The tool will work if the file
Om Stefan.htt. is just a renamed
About.htt., just point to the About.htt file when asked if you want to find the master template. If the template is a custom page then there is nothing to refer to, to convert it.