I have a problem about using Facebook. However, I cannot find a suitable site on Stack Exchange to ask it on. What site should I use?
It looks like Web Apps may be a fit for your question, just judging by "problem using Facebook." However, be sure to read that and other topics in their help center before you post, to make sure your full question is on topic there.
To quote their help center:
If your question generally covers …
- Using Gmail, Facebook, Twitter, Google, or any other website which behaves like an application
- Features of browsers which are directly related to the use of a web application (Greasemonkey scripts for a web application, etc.)
… then you’re in the right place to ask your question!