It depends on which type of activex you choose to use,
normaly every kind of activex has it's own manual,u can find them in their official web sites.
If you want to use some of Microsoft Activex, I suggest you to download the OLE/COM Object Viewer
http://www.microsoft.com/windows2000.../oleview-o.asp
"View type library contents in Oleview to determine what methods, properties,
and events a Microsoft ActiveX control supports... "