Visiting Prauge for first time- questiona about restrooms- where?

plenty of toilets about usually marked WC ,you will see them about ,also see them in shopping malls and in metro stations , cost vary from free in some malls but not all, and from 5kc up to 20kc in some places, standard vary form lovely to bloody terrible.

In order I use 1) Shopping centre free, 2) shopping centre paid, 3) Serviced toilet paid i.e. old lady that looks after it, 4) Hotel. I absolutely do not use the automated booths. Just note that it's pay before.

I love this video from Honest Guide on the subject: https://www.youtube.com/watch?v=UQ9QjQ29aSM

Always take advantage of the opportunity when at a museum. If you're spending a few hours to explore the sites of the Jewish Quarter Museum, they have a WC at the ticket office.