Basically, these tricks are maneuvers and antics performed by skateboarders. Obviously, learning new ticks is always the order of the day.
To do this, bend your knees considerably while you are on the go. Then slam your foot as hard as you can on your skateboard's tail. Now, while you do that, ideally, you would want to jump off your back foot. This will need a bit of practice, which will give you the idea as to how to get the timing right.
As the skateboard hits the ground, leap off that foot. At the end, make sure that your back foot has been pulled high into the air. It has to be quick and snappy. Once you jump in the air, roll your front foot slightly inwards. What you need to do is roll and drag the skateboard.
Finally, just pull both your knees up, or rather as high as you can, and land on the ground. As you land, again bend your knees as you did before you did the Ollie. This is crucial, because this will reduce the intensity of the shock of the landing.
As a result, the board spins or flips minimum once, and the landing is smooth, with the wheels down. The kickflip is much jazzier than the ollie.
Here is where the trucks come in. Trucks are T-shaped metal parts that are mounted on the underside of the board deck. There are 2 such trucks in a regular skateboard, facing each other. Face the ledge or any platform you want to skate on, keeping a fair distance between you and the ledge or rail.
Start skateboarding on a comfortable speed. Have your feet in the ollie position while going towards the ledge―the ball of the back foot should be on the tail, and the front foot above the front trucks. Just before the start of the ledge, ollie up on the object meant for 50-50 grinding.
Make sure you land with the trucks uniformly on the ledge―that is the ledge or rail in the center of the trucks. As you land, remember to bend your knees. Keeping your knees bent while grinding will help you balance. At the end of the rail, have a small pop up, and land on the ground.
Immediately after your front foot leaves the board, point your toes in the air and kick it forward, in front of you. You have to flip and flick the board using your heel, as the name goes. Pull your front foot underneath you to give room for the board to flip.
Stay balanced and keep your weight above the board. Once you flip the board, catch it by putting your back foot on it. Putting your front foot down on the board is a natural following in this step. Now simply land with the knees bent, and roll off.
Eventually, balancing and perfect timing is the key to these and many other tricks. Apart from these, there are quite a few more, but these are good for beginners.