It is common to hear that for backup there is not sufficient space on my server or my server disk is about to full. And now I want to take my RMAN backup directly to remote location. How I can achieve that?

Now before taking backup let think in which type of storage on remote location you want to take backup? Is it a disk or to the tape. Below is the procedure for both types.
http://arjudba.blogspot.com/2008/10/how-to-take-rman-backup-on-remote-disk.html