I am having problem in connecting my Linux system to an existing Microsoft Network.

I have configure the Network interface, but its not connecting.

Could you provide more information on the Microsoft Network, and what you want to connect to? Is it a home network? Is it a network at work or school? If you are dealing with a Microsoft domain, then a network admin needs to add your computer to the domain, and you may need to configure your client as well. Otherwise you won't have access to shares on the network. For a home network, you may only need a samba client, or to offer shares yourself to install samba.

Also indicate which linux distro you are dealing with.
Yours may make it easy through a wizard to configure user authentication via samba, ldap or AD, installing any needed packages and configuring PAM correctly.

Not connecting? What do you want to do?
Set the ip address, mask and other options and try to ping your windows machine. If your linux box is able to ping windows box then you can safely say it is on the network.
But if you want to share files from linux box to windows then you will need samba. If you want to access windows files on linux then you need smbclient i guess.
What distribution are you using and what version?
Some more information will be helpful in helping you.

Edit: Ok, jschiwal beat me by some seconds.