I have completed the signup. I'd like to offer help by pairing. How do I do that? How can I find people who need help now? How can I enter the times when I am available in principle?
Sorry, yes, the design is not very clear and sometimes it is hard to find pairing partners.
You can click on the 'sessions' link in the menu and see calendar with open sessions (there are no open sessions this month). You can add your own session by going to your profile and clicking on the edit link next to the calendar (there would be a page with the 'create' button).
The system does not allow you to contact any user, only ones that have open pairing sessions.
It's not perfect and will change in the future. In a meantime, you can help the project by adding/changing features. It is available on github.
Customer support service by UserEcho