At first, this will show you all hours of the day, which can be confusing - you don't want to set a meeting for 4am instead of 4pm. To change this to only see meetings during working hours, begin creating a new meeting request and click the Scheduling tab. Then, click Options towards the bottom, then click "Show Only My Working Hours", which will limit the hours to 8am-5pm. You will only need to do this the very first time you set up a meeting, NOT every time.
If you need to schedule a meeting earlier than 8am or later than 5pm, uncheck the same option to see the expanded hours. You can also type in the times under "Start time" and "End time", but doing so will automatically set it to show all hours of the day, and you will have to check "Show Only My Working Hours" again to shorten the hours again.