Blocking
To block, hold back on the joystick. To block low attacks, hold down back on the joystick. You can block just about anything apart from throws and command throws, such as Zangief's spinning pile driver. You will not take any damage whilst blocking standard punches or kicks, but you will take a very small amount of damage when blocking special moves. You cannot block in the air.
Jumps
There are three jump types in the game -holding up on the joystick will have you character jump straight up, holding up forward has them jump toward the opponent and holding up backward has them jump away from the opponent.
Throws
Each character has at least one throw technique. Throws are done by getting close to the opponent, holding forward (to throw them forward) or backward (to throw them backward) and then pressing either strong punch, fierce punch, forward kick or roundhouse kick. It depends on the character for which button you need to press, for example, Chun-Li can only throw with the strong and fierce punch buttons. To see what throws a character can do, go to the character section and check each fighter's page.
Stuns
If you repeatedly manage to hit your opponent with attacks within a few seconds, they will be stunned. This means that they will briefly be unable to move or block, so you've basically got the chance to get in a free combo. If you are stunned, press every button to shake off the stars quicker.
Meet the Bosses
BALROG
After you defeat 7 opponents, three new characters will appear for you to fight. The first of these is Balrog, an American boxer who works for Bison as hired muscle. Banned from his boxing for his violent behavior in the ring, Balrog can hit hard and fast. His main form of offense is a dash punch, where he dashes towards you whilst delivering a mighty strike. He can do this move repeatedly and trap you in the corner.
He has a variation of this move where he hits you with an uppercut, and yet another version where he will spin around for a few seconds to charge up his power -this is his most devastating punch if it hits you. However, Balrog is quite an easy boss as you can easily hit him as he dashes towards you, just use the crouching roundhouse kick to keep knocking him over. He isn't very smart and will often happily walk straight into jumping attacks, so keep that in mind when fighting him. Also, if playing as Zangief, just do nothing but spinning clotheslines and see what happens.
VEGA
Vega is a Spanish matador who has also mastered ninjitsu. He is the second boss and is no joke, unlike Balrog. His jump kicks are extremely powerful and difficult to overcome, and his talon gives his punches much more reach than other characters. He also has a slide kick he can knock you down with, and a special move where he does a couple of forward rolls followed with a stab. He is also capable of avoiding attacks by using a back flip, but if you can get close to him when he does this, you can throw him as he recovers from this move.
Sometimes Vega will leap back and climb up the cage in the background. After waiting a few seconds, he will leap at you and has two different attacks. One of them is a swipe which can knock you over, but he can also pick you up and then slam you into the ground. Vega's main weakness is that if you jump towards him and quickly press the roundhouse kick button, Vega will often try and jump up and try and kick you, but fail.
SAGAT
Sagat was the strongest warrior in the world...but at a previous tournament, he was defeated by Ryu and scarred for life when he was hit by a shoryuken. Having trained hard, he now returns to fighting and serves as the penultimate boss in Street Fighter II. He still has his fireballs, but he can now throw them high and low. He leaves himself wide open when using these, but he can throw and recover from them quickly.
But his main technique is a new move called the tiger uppercut. Never randomly jump at Sagat as he will always use this devastating punch, which does a lot of damage. His jump kicks are also powerful and most of his punches are extremely fast and damaging. The main way to beat Sagat is when he starts throwing out tiger shots repeatedly -he will usually throw a high one followed by a low one, so jump towards him and time an attack as he is using one of his projectiles.
M. BISON
After defeating the three bosses, you will face the final one: Bison. Not much is known about him other than that he is the leader of the evil terrorist group Shadaloo. And as you might expect, he is very powerful. His signature attack is the psycho crusher, where he charges forward spinning whilst surrounded by an aura. If he touches you, you will be knocked to the ground whilst covered in blue flames. His jump kicks are also very effective.
Another move he has is the knee press, which is a 2 hit kick which he can do repeatedly, often dizzying you with ease. He can also stomp on your head, watch out if he suddenly jumps up towards you. I haven't got much advice for taking on Bison, but you can tell if he is going to use his psycho crusher as it takes him a second or two to charge up before doing the move. You can often hit him before he gets the chance to do it. Also, if you hit him whilst he is doing the move, he suffers a massive amount of damage.