How do the stages look like in the medieval period?

Answer 1

For most of the Middle Ages, and in most parts of Europe, theater was done outdoors. There were very few buildings that were intended to be theaters, perhaps there were none in Western Europe.

Theatrical productions, however, were done throughout the Middle Ages by various groups of people who travelled around, very much as modern circuses do. They very often had large wagons called pageant wagons, some mounted on six wheels, and these were used as stages. The productions were done in courtyards, at fairs, and in areas of the countryside that were naturally shaped well for audience viewing. In England, where there were rood screens in the churches, theatrical productions were sometimes done in churches, if they had suitable content.

There is a link below to more on the medieval theater and staging.