Hey, thanks for your interest in contributing, we always welcome new input and apologies if the process isn't very clear.
I'm assuming that you've already checked the files against the existing TOSEC database using a ROM manager (e.g. clrmamepro or ROMVault) and that they are not currently included?
If so, the next thing to do is to sort the files into their relevant system/category/file format (so e.g. IBM PC/Games/IMG) and then rename them according to the
TOSEC Naming Convention. Once that's done you can generate a DAT file which will have all of the unique hash info for those files and we can include that in the relevant DATs.
The usual process is that you then post those DATs (*not* the files themselves) in the Errors & Contributions section of the forum. One of the team will then check them over, see if there are any issues or errors etc. to be fixed and then we can integrate them in the next release.
Appreciate that reply has condensed a lot of work down into a couple of quick sentences, but more than happy to help or explain in more detail if you're not sure about what any of the above means or how to get started.