Do not request that the invitee share their calendar with you (see the sidebar for information on why this is inappropriate). Instead, follow the instructions below for the appropriate version of Outlook.
Click the Calendar button.
Your calendar and appointment data appears.
From the "New" menu, choose "Meeting Request"
The "Untitled - Appointment window" appears.
Click "Click here to add name" and (no surprise) type the person's name who you'd like to schedule for the meeting.
Assuming Outlook can find the person's calendar (their name will appear with an underline if so), their busy/free time will appear next to their name, under your own. Repeat with as many invitees as necessary.
Click "AutoPick Next >> to let Outlook find the next open time for all invitees.
Click "Send" to add the meeting to your calendar and send an invitation to the invitee(s). (If necessary, you can click the "Appointment" tab and adjust the meeting information before sending it.