If you mean launching a UserForm, then using a button drawn on the sheet from the Control Toolbox:
<font face=Tahoma><SPAN style="color:#00007F">Private</SPAN> <SPAN style="color:#00007F">Sub</SPAN> CommandButton1_Click()
UserForm1.Show
<SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">Sub</SPAN></FONT>
HTH,
Smitty