Ummm you obviously have your head under a rock, i'm pretty sure there are people here that can't do shit on skis they just post the forums to troll. And there are plenty of people in the trick tip cult asking how to slide rails all the time. Just like him.
Anyways to answer your question the easiest way to learn rails is to learn to pop turn 90's and then when landing on the rail make sure your weight is somewhat balanced but if anything have more weight distributed towards the lead foot to prevent sliding out. Make sure that you stair the end of the rail down all the way to prevent sliding off early, as well as keeping your shoulders perpendicular to the rail to make sure you don't end up nutting yourself. You will want to try this on box first as it is a lot easier to practice on. If you need anymore advice there is the trick tip cult with pictures and other people's questions and responses to help you. Good luck man, once you learn how to railslide you'll be on your way.
holy shit you guys r dumb asses i know how to grind im welding a rail and wanna know if you can slide iron for the guy that anwsered my question thank you but to the rest fuck you