Using Visual Basic for Applications (VBA) in Excel
STEP 1 Create a new Excel workbook.
STEP 2 Go to View/Toolbars/Control Toolbox.
The Visual Basic Toolbox appears on Sheet1.
STEP 3 Select the Command Button tool from the Toolbox and draw a button on Sheet1.
STEP 4 Move the
cursor over the Command Button you just created until it turns into a four-way
pointer ( 
)
STEP 5 Double-click the Command Button with the four-way pointer. The Visual Basic window appears ...
STEP 6 Insert the Goto method as above:
Application.Goto Reference:=Worksheets("Sheet2").Range("A1")
STEP 7 Click the Run button
STEP 7 Close the Visual Basic window and return to Sheet1. Click your new Button and you will be switched to Sheet2.
Repeat the steps above to make a Button on Sheet2 that will take you back to Sheet1.
NOTE: If all you want to do is go between sheets, it may be easier to use the built-in Hyperlink technique, rather than VBA - Thanks Jody for the information.
Related VBA Sites:
http://www.scottm.dircon.co.uk/vbatips/
http://www.vbatutor.com/
http://lacher.com/