Skip the guide.
Fill-in name and email, click continue
Thunderbird finds servers (imap.stud.fit.vutbr.cz and smpt.stud.fit.vutbr.cz), click Finish
That's all.
Setings->Options->Options - here you can turn off Global Search and Indexing. It saves a lot of space in your profile.
Send comments to michal@fit.vut.cz