how can i do redirection using htaccess (for examle after 30sec. it will open www.webhostingtalk.com )

I do not know how you can do 30 sec wait in .htaccess
But for redirect you can use:

redirect / www.webhostingtalk.com

I actually think you can't do that with .htaccess. You are going to have to use javascript.

Found this for you: http://www.pa.msu.edu/services/computing/faq/auto-redirect.html

Im not sure you can do it with .htaccess but the redirect script is

Redirect permanent / http://www.yournewsite.com

Or you can use this code in html pages to redirect

<meta
http-equiv="refresh" content="30; url=your new address.html">

yeah, theres no such thing as a "timed" redirect in apache, so if i were you, id use the meta tag as rlhosting said.