How do I open available hours?

منذ ٥ أعوام

Hello my fellow teachers!
I am brand new on this platform and was wondering how to open my available teaching hours. What I mean is, that I do only from full to full, but not .30 to .30 or any other minute constellation.
On my calendar I marked "available" only the full hour fields (not the half hour fields below) so that I avoid students booking from .30 to .30. 

Or should I mark both fields as available?

Also, in case you see something "weird" on my profile, please let me know so that I can apply the changes necessary.

Thank you for your information!