is it possible to set up mutiple subdomains not in the form mysite.com/abc BUT abc.mysite.com in raq servers ? any online faq/tutorial for that ?

No tutorial needed. Simply set up another virtual site with a different host name. Normally you'd enter 'www' for the host name and 'domain.com' for the domain. Instead, enter 'subdomain' for the host name and 'domain.com' for the domain. You will have to add an A RECORD for the domain for this host name as well, pointing to the IP that you are going to set the subdomain up on. Make sure this matches.

If you want to set up subdomains on the fly, so to speak, then wildcard the domain to an IP address and set up subdomains on that IP and they will be active immediately after you create the virtual site.

then wildcard the domain to an IP address
please explain this

What wildcard is, or how to do it? What are you using for DNS now (the server itself, some other service for DNS, etc.)?