[KabaKun]

Earning reputation on Stack Overflow can be a really slow, tiring process. As others have mentioned, suggesting edits is one way to get there. For each that gets accepted, you earn +2 rep. I earned 25 rep this way and it was a slog.

The easiest way to get 100 rep on SO, though, is to get 200 rep on any other site on the network. This is called the Association Bonus. Enjoy movies or cooking or video games or board games? Go post questions/answers on those sites and get some votes. There are 170+ sites on the network and because they're lower-volume, earning rep is often faster because posts are more visible.

I'm not sure which sites you've tried so far, but it is possible to do and even have some fun doing it.