"Are they showering now?"
Translation:¿Ellos se duchan ahora?
It looks like you attempted to do the present continuous in this translation. That is good. In Spanish, the present continuous is formed from estar + the present participle. So you need the present participle duchando instead of the infinitive duchar.
You could do ¿Ellos están duchándose ahora? as I already explained elsewhere in this thread, or ¿Ellos se están duchándo ahora?