trying to monitor incoming calls and try to get the caller's number,, don't know which event handle incoming calls and caller's number?

The API documentation and sample scripts can help you,
https://developer.skype.com/Docs

i had took a peek at the api doc, but the api doc is not detail enought to tell what are the uses of each function..

Here are to examples, one shows call history, the other shows real-time use of call status using the Skype4COM lib:

Call History

http://testing.onlytherightanswers.com/skypebeta/Calls.htm

Real-Time use

http://testing.onlytherightanswers.com/skypebeta/Client.htm

Both are done using JavaScript and Internet Explorer just view the HTML source.