I have installed IIS and configured ASP.NET and PHP for it, on my PC.

now how to configure IIS to make the webpages in the "wwwroot" folder on my computer accessible to others on the internet using my IP address?

say if my IP is something like 61.1.159.189 then the link http://61.1.159.189/index.html must be served by my webserver.

I would be glad if you can include instructions for same for Apache web server.

Also which is more prefferable LAMP r WAMP? I am a novice LINUX user.

There is a lot involved with this answer but here is the short version that should get you pointed in the right direction.

Find out if your IP address is static or dynamic. If it is static you can always use the same IP address but if it is dynamic it may change on you over time making it hard for others to access.

Inside IIS under the default website, create a virtual directory. Give it a site name and then select the folder location where you have your site stored. If you want to use just your IP address as the site than just make sure you have everything in the wwwroot folder and don't worry about the virtual directory.

Next you have to make sure port 80 is not blocked by your PC or any firewall you have installed. If you happen to have a router you need to make sure that port 80 gets forwarded to the internal IP address of your machine hosting the site. If your PC is connected directly to the internet you won't have an internal IP address.