Where is the ...

Microsoft.SharePoint.dll:

C:\Program Files\Common Files\Microsoft Shared\web server extensions\12\ISAPI\Microsoft.SharePoint.dll

New GUID (guidgen.exe):

C:\Program Files\Microsoft Visual Studio 8\Common7\Tools\guidgen.exe.

CMD:

C:\Program Files\Common Files\Microsoft Shared\web server extensions\12\BIN

PublicKey Token:

To get the Public Key Token of the assembly, in Windows Explorer find the MyEventHandler.dll file in the C:\WINDOWS\assembly, right-click the file, click Properties, and on the General tab of the Properties dialog box, select and copy the token.

Installing EventHandler:

stsadm -o installfeature -filename dirwhereeventis\Feature.xml

stsadm -o activatefeature -filename dirwhereeventis\Feature.xml -url http://Server/Site/Subsite

iisreset

*dirwhereeventis = C:\Program Files\Common Files\Microsoft Shared\web server extensions\12\TEMPLATES\FEATURES\nameofdir