If I understand your question correctly, you want to be able to double click a file in an explorer window, and open it with your own application rather than whatever windows normally uses?
If so, you can achieve this by modifying / adding a file type (used to be called associations). If you select the tools menu -> Folder options -> File Types, you are presented with a window listing the current registered file type by suffix. From here you can modify the application used by default to open specific file types. Another simpler way is to selectg the file that you wish to open, right click on it to bring up the context menu, then select open with. In the ensuing selection box, there is a tick box to 'always use this program with this file type'
If this isn't what y
ou were asking please excuse my ramblings and provide more details 😉
Regards
John