how to create a login page using picture password? not captcha.. ex:- select a picture and click any four points. these points stored into database in an encrypted format . how do it?

Finding the actual mouse position is harder than you might think - the various different browsers do it in different ways (and it obviously has to be done at the client). This may help you: http://docs.jquery.com/Tutorials:Mouse_Position[^]

But personally, I wouldn't. Why not? Because what are your users going to do when they don't have a mouse? A Tablet, or smartphone for example.

The other approach might be to divide the image into parts: if you make it into nine separate images then it is easier to work with as they just need to touch the appropriate part image - which can have it's own event. Depends how accurate you want your users to be how many images you need.

Interesting. You want something like the android "pattern password" with 3x3 point? Heer is a javascript library to do that: http://blog.stef.be/patternlock[^].
But you will have to pass the "password" to an input field on client side, and send it as any regular credential.
I suggest you use the authentication facilities shipped with asp.net, more precisely the forms authentication[^]. As membership and role provider you can use any (or custom), but I suggest you start with the sql based one[^].