Head over to your Calendar tab and select Availability inside the My Events menu in the top right corner.
Here, you can set the specific hours that you are available for any specific day by selecting that day.
Or you can add the hours for every day of the week in that month by selecting the drop-down menu at the top of each day. For example, all hours added on Wednesday will carry over to every Wednesday that month.
The settings you add at the top of each day get applied indefinitely to all months and years.
That's all there is to it, you've now set up your availability settings.