Hostel Identity Provider (IdP) is a service provided to users coming from institutions that are not members of the Czech identity federation eduID.cz or the European federation eduGAIN. Authentication using federation is much more easier than authentication using Hostel IdP, so if you work for an institution that is already a member of some federation, you already have own IdP and you do not need to use Hostel IdP.
If you really have no other choice, use the Hostel provided by CESNET (the Czech academic network consortium).
Registration to Hostel IdP
More information about Hostel IdP can be obtained on the Hostel pages.