Assuming you are using resources create two base calendars:

Day Shift
Project ribbon - Click change working time.
Click Create new Calendar to create a new calendar.
Name it "Day Shift" (or whatever) and click OK to create the new calendar.
In the Day Shift calendar click the Work Weeks tab and select the only entry - Default.
Click the Details button to open the details dialog
In the Details dialog select Sunday through Saturday.
Click the Set day(s) to these specific working times.


In the From section type 7:00 am and in the To section type 7:00 pm.
Click OK to close the Details dialog and return to Change Working time.
Click OK to close the Change Working time dialog box.
Save your project file.

Night Shift
Project ribbon - Click change working time.
Click Create new Calendar to create a new calendar.
Name it "Night Shift" (or whatever) and click OK to create the new calendar.
In the Night Shift calendar click the Work Weeks tab and select the only entry - Default.
Click the Details button to open the details dialog
In the Details dialog select Sunday through Saturday.
In the From Section type 12:00 am and in the To section type 7:00 am.
In the second row enter 7:00 pm to 12:00 am.
Click OK to close the Details dialog and return to Change Working time.
Click OK to close the Change Working time dialog box.
Save your project file.

On the resource sheet view create your resources and select either Day Shift or Night shift as their base calendars.