skateboarding.....man i don't think i've skateboarded in like 4 years or so. i used to be actually pretty decent. i don't remember a whole lot, but i know that skateboarding takes a lot of practice, and lots of bruises to get things going.
you say you are having problems even going...well this has to be your first goal, to keep your balance and to push off and go. just ride around the neighborhood a lot and you will get better at that.
i next recommend after you learn how to skate better, to learn how to ollie, which is essential for doing all sorts of street tricks such as kickflips, hardflips, impossibles and so on. like i said, i haven't done this in a while, but for ollieing, you need to push back on the tail hard with one foot. then with the other foot, slide it sideways up the board to level the board out and also be up in the air.
im not going into other detail because you need to get these things down first before you can expect any other kind of maneuvers.
hope this helped