you need to be a little more specific. are you trying to mount a shared folder from another computer? what OS is that other computer running? what OS are you running? (fedora, debian, ubuntu, etc). depending on your OS, to mount a shared folder on a remote windows computer, you could do something like this:
sudo mkdir /mnt/folder
sudo /sbin/mount.cifs //192.168.1.15/folder /mnt/folder -ousers
where //192.168.1.15/folder is the shared folder you want to connect to, and /mnt/folder is the local folder you want to mount it in. obviously, change the IP address and "folder" to match whatever you are connecting to. if you want it to always mount automatically when you reboot, you could add this to your /etc/fstab file:
//192.168.1.15/folder /mnt/folder cifs users 0 0
depending on how the folder is shared, you may also need to provide a username and password. if that is the case, post up and I'll show you how to provide those.