Dear Jirka Daněk,
Thank you for reaching out to the Wikimedia Education mailing list. It's great to hear from you and I am happy that you are interested in using Wikipedia in Education! :)
Yes, the Czech Chapter are the right people to talk to. They are wonderful and their WEP (Wikipedia Education Program) is strong and long-standing. They will be excellent advisors to you and your students. I am cc'ing Vojtěch Dostál, who is not only a long-time Czech Wikipedian, but also a mentor in our international Education Collaborative. He will connect you with the right contact in the chapter.
I'd also direct you to this page on Outreach wiki, where the Global Education Program lives. It links to the various online trainings available to help onboard you and your students.
Sincere thanks to Kavya, Amir, Leigh, and John for their very helpful replies.
Please don't hesitate to reach out to us again for more support!
All the best,
Anna :)