how can we fix a particular portion on the webpage so that if we scroll or something happens in webpage it remains as it is.

Answer 1

If you mean the background, use CSS:
body {
background-position: fixed;
}
If you want an object not to follow the rest of the page, also use CSS :) fixed positioning:
div {
position: fixed;
top: 0;
right: 0;
}

Answer 2

please repeat your question in a specific way

Answer 3

we can use position :fixed in the css of the div we want to fix

Answer 4

use firebug to disect/examine your website