Class Dates
To edit your Class schedule, navigate to the Classes page (this may be called something else if you've customized it, i.e., Sessions, Groups, etc.).
Click on the pencil icon in the upper-right corner to edit the Class. Scroll down to the heading "When Class Happens" Here, you can edit the start/end times and the days/dates the Class occurs.
Weekly Schedule
This example is for a Class that occurs every Monday, Tuesday, and Wednesday from December 6 to March 30:
Pick Dates (doesn't recur)
This example is for a Class meeting on specific dates: