I have placed my php i file inside htdocs folder and when i am trying to access it an error message is displayed.
Not Found
The requested URL /first.php was not found on this server.
My wamp server is online also.
I suggest you to use some software, which has everything ready, that way it saves a lot of time installing the crap. “easyphp” is free and easy software for that. Just google it.
…Good for development. Not good for production. Anyway, that aside.
OP: if first.php is reported not to exist, you’ve put it in the wrong folder. Simple as that. I’d suggest you go in your Apache config and check where the document root actually is.
I think, you should create HTML-folder inside htdocs and then copy the respective PHP file inside the HTML-folder.
Then you can access PHP file from browser.