To do a darkside grind set up in a kickflip stance. Like all grinds start heading towards what ever you are going to try it on, with an angle. When you think you are close enough to your rail, ledge, etc. you want to do a kick flip, but don’t kick it as hard as you would for a kickflip (you only want half of the rotation). At the same time sweep your back foot just a little bit behind you (you want your board to turn 90 degrees). You also want to turn your body 90 degrees. Once you see that you board has done half of a flip and rotated 90 degrres and you have turned 90 degrees, catch the board with your feet . Your front foot should land on the bottom side of your nose and your back foot should land on the bottom side of your tail. Land with the rail as close to the middle of the board as you can. When you reach the end of the rail twist your body 90 degrees, then tap the heel side edge of the nose with your toes to start fliping it. Once the board has rotated 90 degrees and flipped half way catch it with your feet and ride away.
A boardslide is a type of grind. Its is also very easy. To do a boardslide, come up to what ever you are going to try it on with a slight angle, and do a 90 degree ollie. Make sure what ever you are grinding is in the middle of your board. And also make sure you have even wieght on both of your feet. You also want to keep your balance. Then once you get to the end of what ever you are grinding just twist your body 90 degrees and land. Pretty simple stuff.