ha ha ha ha I want to think where the nervousness.
No, Castillian is a language close to Spanish, castillian is the variation from Spanish speaked on «Castilla» a "state" of the kindom of Spain, spanish is the most used variation. even spanish is the one speak on American continent.
Spain is a «country» made from several «states» called (comunidad autónoma -commonwealth-) and on each one they inhabitants speaks different languages but all of them also speak spanish.
yes, Martes and Miércoles (Tuesday and Wednesday) but coincidencially on spanish also there are only two months which names start with «m» Marzo ad Mayo (march and may)