I have used my own scene transitions not using a preset template. Now I want to make a Menu Select Scene (manually, I guess) but don't know how Can anyone help me, please?
Custom Menu Sets (note: PrE uses Menu Sets w/ a Main Menu and a Scene Selection Menu, and there are several necessary conventions, from file names to the layout, that MUST be followed, due to PrE doing much of the authoring semi-automatically), and it's almost always best to start with one of the included Menu Sets, and then adjust that in PS, or PSElements, following the exact conventions in the Template. Note: PSE cannot create Layer Sets, so you cannot create Buttons, but can do some Copy/Paste work. The full Photoshop has no such limitations.
Whenever I need to create PrE Menu Sets, I will either start with a Template, or will at least have one Open, to make sure that I do not forget any of the necessary conventions.
For some background on PrE Menu Sets, this ARTICLE might prove useful.
For some additional discussions, this ARTICLE on Motion/Audio in Menus, might be useful.
Steve Grisetti goes into great detail on PrE Menu Sets in his PrE & PSE books.