How do I get a macro to run in Outlook 2010?

You need more info for me to give you a good enough answer, but here's a quick overview of what I did and was successful to get a macro going.

If you're looking to have a macro run based on an event:

This means you're looking to have your code run based on events that happen within outlook. For example, Application_Startup.

Under the Developer IDE (Alt + F11) select Microsoft Outlook Objects -> ThisOutlookSession

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Then Select the dropdown that says General and Select Application. You'll then be able to select all the event driven methods that you can add. For Example:

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If you're looking to just run a Macro

In the IDE, select the toolbars creation button dropdown and select Module

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Within the code, create you're module:

Sub test()

    MsgBox "Hey Look a Macro!"
End Sub

You can then run it from the Developer tab:

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Note: You have to make sure that you enable ALL macros in the security center

For more information I would highly suggest you read up on the Developer's website material.