Nick,
I presume you mean in Excel, not on a userform?
Three ways:
Make sure the Forms menu is open (Tools>Customize>Toolbars), click the
button control, then on the worksheet right-click and size the button. You
will immediately be presented with a dialog box to assign a macro to he
button.
OR
Make sure the Control Toolbox toolbar is open (same way), click the button
control, then on the worksheet right-click and size the button. Then double
click the button and you will be taken to the VBE with a button click event
macro set-up where you can call your macro, or even add the code there.
Click the Design mode button on this control to exit Design.
OR
Add a button to a toolbar (Tools>Customize>Commands) and select the Macros
option, then drag either the smiley or the text item onto an existing
toolbar. Right click the new button, and there is an option to assign a
macro.
--
HTH
Bob Phillips
... looking out across Poole Harbour to the Purbecks
(remove nothere from the email address if mailing direct)