Web security and Updating a web page

[Venkat]

Hello Everybody!
I am a learner of web development. I know HTML,DHTML,Java Script. What
else i have to know for good web developing?
(1)I am given the task of updating the already existing web page of a web
site.I have to provide security for certain pages.How to do this?
(2)Some of the pages need data from tables in MS ACCess.I need code to accomplish
this.
(3)After completing a website, how to launch it in the net?

Thankyou very much.