XProfan

you mean, You want for your Program a File extension Register, so that later with a Double-click on so a File your Program called becomes, around the File to open?
For this are different Entries in the Registry necessary.

under "HKEY_CLASSES_ROOT" (HKEY_0) must You a Key produce, the your Endung corresponds to (with vorangestelltem .. there must one entry of type Zeichenkette present his, the on a further Key under HKEY_CLASSES_ROOT verweist. The is then xyzfile.
under this Key go against Unterschlüssel prepares:
- DefaultIcon (here becomes the Exploreransichtsicon tuned
- Shell
- - Open

on the best, you see you the times for whom type .txt on. this is crept and slight nachzuvollziehen.
You can also a File meineDatei.xyz create and then through "öffnen with..."And "Datei always of these Program öffnen" automatically a entry create let. If you the then from the Registry copy, know You, what You present must. thereby becomes then though The Bezeichnung autofile uses, The You by a selbstgewählte Bezeichnung supplant should.

you become probably Admin-rights for your Program need, if you such Entries distinguished want.

I hope, the helps you first time moreover. I Have in the momentum too none code for parat but writeini "HKEY_0",... is thereby your friend.

If you here time to "Registry" seek, find You a crowd Entries, The you help could.

so - Have time short what zusammengeschrieben:
CompileMarkSeparation