Create a Mailing Group in Outlook Express
In Outlook Express open the Address Book on the Menu Bar at the top of the program.

Select "New" then click on "New Group" on the drop down menu.
Type the name for your group in the "Group Name" text box and the click on "Select Members". In this example we have called our group "Test Group"
In this step we select members for our group from the addresses in our address book. To do this we hold down our "CTRL" key and select each person with our mouse. If you accidently select the wrong address, just click on the address again to un-select it.

When you have selected all the members for your group, click on the "Select - >" button to transfer them into the members column. Final step is to click on OK.
If a person that you wish to add to your group is not in your address book, you can click on "New Contact" and manually type in their address. Also you can remove any members by highlighting them (Click on their name) and click the "Remove" button. Click OK to finish.
Anytime you wish to edit your group just right click on the groups name in the address book and select "Properties" from the drop down menu.
How to use your mailing group to send mail.