How do i make an option set save a list

Hello guys,

so i have an app where users can create venues.
now i want users to be able so select the days of the week they’re going to be open.

to do this i created an option set called “days” and put in the days of the week as the options
on my design page, i created a drowndown and set its “type of choice” to my option set “days”
but now i want the user to be able to select more than one day and i want the days they select to e displayed as they select it, maybe as the place holder of the dropdown. please how to i do that?