Ok, so you want to start skateboarding, the first thing you need to do is the gear. Skateboarding is a big sport now and a lot of companies are trying to get noticed, lower there prices is one thing they do, it isn't the best idea to by a Walmart or Zellers skateboard and now a days you can usually get a really good board for a low price. Go to a local skate shop and tell the guy you want to start skating but don't have lot's of money. He will probably point you straight to the decks, the blank decks. I know when you start skating you want pictures but later you will realize it's not a big factor of buying a deck. Look at the deck, now you have to know something to judge if it is good or not. First thing you want to look at the width, it should be big enough so that when you step on it your feet hang out on both sides, I would recommend starting with a 7.5" deck. Most people like that size and keep with it the whole time they skate. Then you should look at the concave, (the dip in the board, it helps you flip tricks and it feels nice) it doesn't matter much at the start, later you will find out if you like them or not as you go through decks and try other peoples boards. If the deck look alright just take it, black decks are usually cheaper then decks with pictures. Now you need some trucks, all trucks pretty much cost the same, but if there is no picture they can cost less. I would recommend starting with something durable, strong and that turns well. Independent's are a good choice. For a beginner all wheels are the same, only the color and picture are different. A good choice of wheels are bullets, they are blank wheels (even though they do have a little picture) and they are really hard, but not too hard. They last forever and don't chip, plus they cost less then most wheels. Next are bearings, you will find that most bearings are rated ABEC 3, 5 or 7., For a beginner 3's are perfect, even for people like me that have been skating a long time ABEC 3's are still good. A good type of bearings to start with are Reds. A lot of people like them, they aren't bad and they don't cost too much. Everything else won't matter as much, hardware, risers and grip tape don't matter a lot.
Having skate shoes helps a lot, they are designed to be wide and stable so it is very hard for you to land on the side of you foot and damage your ankle. They are also designed to withstand the way you treat them when you skate. Now since skate shoes are one of the biggest style of shoes you will see lot's of people wearing them and many new companies are coming out. If you go to a sports store and look at some shoes I will pretty much guarantee you that you will find some kind of skate shoe. Sports stores have great shoes, I admit I used to by shoes from there, I find they last longer then some of the more well known companies like DC or Osiris. These shoes that I am talking about (the sports store shoes) are really cheap too, you can get shoes around $30 U.S.D. that will last you up to four months of really tough skateboarding. I once bought shoes for $35 U.S. and they lasted me four months, of skating every day for at least one hour after those four months they just started to rip and they got there first hole. Another time I bought these shoes that I saw advertised in a magazine for about $60 and I put in 3 holes where I drag my shoe for an Ollie in less the an hour of skating. These shoes that I am telling you about the ones for cheap also look nice, some of the shoes that I see at these sports stores you can tell that they are based on shoes that cost tons of money the kinds you see in magazines that cost a lot and look really nice. The cheap shoes look a lot like them. Anyway I HIGHLY recommend buying these cheap skate shoes that you find at sports stores, most of them are around half the price of a running shoe.
Ok now you have your skateboard, and some shoes it is time to learn some tricks. The first thing you want to know how to do is push and ride and manual a bit to get a sense of balance. This might take around a week to get good at. Just ride to school everyday or something and eventually it will be like walking. First trick you want to learn is an Ollie, the jump of skateboarding. Go to the trick tips to see how to learn that. Next you want to learn the shove it and then a F/S 180. After you learn these it is time for the hardest part of being a beginner, learning how to kickflip. Once you have that trick down, most people won't think of you as such a beginner. Then you are ready to go to skate parks and start learning grinds and board slides and doing some gaps.
Good Luck!