To make regular weekly blocks of scheduled time go to:
Schedule > Templates. Left click and highlight the block of time that you wish to block out. Then right click blue area > choose "Blocked Time" and it will give you choices.
If you do not see your choices you can add them at the very bottom.
Weekly blocks should always be done in templates. If it is a one time block of time that needs to be blocked out you can do the same procedure on the daily schedule.
Should you wish to unblock time simply right click on the desired block of time to open up and select the delete option.