It's really easy to understand it even if you don't speak french, though.
To sign up you need to click on the red "créer ma ville" button, click on a region on the map (they're all the same, more or less, some are more popular and it's harder to get on the high-scores if that's what you care about) and pick the name of your town. After that, you're done. You'll get your city's link (which will be in the form
your-city's-name.miniville.fr)and you can click it to get more citizens. After you get enough people (50, I think) your unemployment ("chomage") will rise and you'll have an option to click a second link (
your-city's-name.miniville.fr/ind) to get more industries and lower the unemployment. If it gets too high, one of your citizens will leave. With more citizens you have even more options of getting better transport, lower the criminality and the pollution, and such. The downside is that you can only do one click per day per city, so you can't for example get another industry AND another citizen on the same day.
Conclusion: I'd love you forever (or until I forget) if you could
click on this link because my unemployment level is sadly getting too high