how to use online simulator. actually i dont have admin privilege in my office so i can't install vmware. anybody help??

Well, first of all, welcome to LQ.org (Still a newbie myself, but already greeting new members ). What online simulator would you like to use? Here, at Linuxquestions.org, there are many people with many professions, skills, distros and even some differend Unices - you can get help much quicklier if you post the distro, version and software you'd like to use. Also, if you want to know something about a resource on the net, a url to it can't be wrong.
Don't see it as an offense or something - I'm just trying to help you. If you post that information, as said, many people will be able to find your thread and help you out, if they can.

actually i want an online url. where i can run linux commands and feel linux environment.

and thanks..thelinuxist

No problem.
A short search on the web pointed me to this page: http://cb.vu/, which seems to be what you seek.
Also, what would be possible if you can't/don't want to use virtualization, you can use Cygwin or MinGW, which can provide a bash like environment to a Windows computer. They're actually made for building software more easily, but all the "standard" commands of a normal bash are implemented as well... Gets close to "real" linux.
Last but not least, you can use a live distro like Knoppix, Puppy or many more of all those out there. I like to use this kind of distro, because I can use "my" OS on any computer, no matter if it's running Windows, Linux or no OS at all.
Of course, before you install or run either Cygwin/MinGW or a live distro, ask your System admin if it's OK, if you want to do it at work.

Oh, and before I forget: Have a lot of fun! That's what Linux is all about.