I just copied all the files from another server.
Exported the database tables and imported them again.
Changed the mainfile.php and I got some of the page working.
I also tried to copy the premissions needed, but it had no affect.

Most files are now on 775. are there any that need 777 or 644 or ...?
Are there files/folders that should not be 775?
I'm a bit lost. Can anybody give me a link to a summary.

The first installation (that I'm copying now) was done by someone else. I'm trying to do it myself, but this method of copying is not giving me that neat installation process.

greetings erik

These folders and all files in them:
xoopsroot/cache
xoopsroot/templates_c
xoopsroot/uploads

should be CHMOD 777 (or any other way, which is writable by the server - you may not need 777, but often it's the case... depends on how the webserver user is setup)

mainfile.php CHMOD 444 (when the information in it is correct)

Rest should be readable, but not writable