You can set a different schedule for different days of the week. To do this, go to add a task as usual by going to Plan -> Schedule -> Add Task, choosing the task type you want to add, then:
When asked how frequently you'd like to be reminded to complete this task, choose Specific days
Pick the days you want to set the same time for (example: Monday, Wednesday, and Friday only).
You can then repeat this to set a different time for the other days! You may need to go back to edit older tasks you created. See more information on how to edit and delete tasks here.