condition to add events

hello

i use the light box and i add some drop down list in the light box.

in thise drop down list, i have some choice…

but this choice shoul depend of the date,

for exemple if i say that english curse is only the tuesday afternoon
and if i want to add a event on wednesday , the choice of course can’t be english, because it’s not the tuesday afternoon. i join a picture with the exemple…

then to summary , i want that the choice depend of the day…