If you mean that you actually want it to open upon start up
Click the Start button, click All Programs, and then click Microsoft Office.
In the list of available Office programs, right-click the icon of the program or programs you want to start automatically, and then click Copy on the shortcut menu.
In the All Programs list, right-click the Startup folder, and then click Explore on the shortcut menu.
In the window that opens, click Organize, and then click Paste.
Don't know what happened to that post - here is the proper version:-
Click the Start button
Click All Programmes,
Click Microsoft Office
In the list of available Office programmes right-click the icon of the
programme you want and then click Copy on the shortcut menu.
In the All Programmes list right-click the Startup folder and then click
Explore on the shortcut menu.
In the window that opens click Organize and then Paste.