The Basics. [ Can you suggest an improvement? Do so here. ]
Streetfighter 2 is played by using the controller to make your character move around the screen, walking, jumping and blocking, and by pushing three punch buttons and three kick buttons of varying strengths. Your object is to deplete your opponents energy bar before they deplete yours.
1. Blocking 2. Jumping 3. Attacking 4. Throwing 5. Special Moves 6. Super Moves
7. Tick Throwing 8. Reversals 9. Move Cancelling 10. Character Selection
To block, pull the controller into the opposite direction your opponent is standing in. If their character is on the left, you pull right, if they are on the right - you pull left. You cannot block while jumping or attacking. You can block while ducking by pulling diagonally away from your opponent. Before you start playing start a game against the computer and practice blocking. Normal moves do no damage when blocked, special moves do a small amount of damage. You are vulnerable to being thrown when blocking. A standing block will block normal standing attacks, overhead attacks and jumping attacks but not low attacks such as sweeps. A crouching block will block low attacks and normal standing attacks, but not jumping or overhead attacks.
To jump push up, up and forwards or up and backwards on the controller. you can attack while jumping. Heavier punches or kicks tend to require tighter timing, and have lower priority than lighter ones.
Your basic three punches and kicks are divided into light, medium and heavy. There are other terms for these, but they most easily understood thought of this way. Light attacks are faster and do less damage but tend to have good priority. Heavy attacks do big damage but often have low priority and are slow to execute. When throwing fireballs, light attacks do slow ones, heavy attacks do fast ones. if your character moves during a special, they will move further with a heavy attack than a light attack but have better priority with a light.
Throwing is a special kind of attack, usually done by pressing towards your opponent and a heavy or middle kick or punch. If done correctly your character will grab their opponent, then either hurl them across the screen or repeatedly hit, knee, bite or headbutt them. If you are grabbed in this way, waggling the stick while pressing all the buttons alternately can release you more quickly. If you are thrown, quickly pressing away and kick performs a tech move, allowing you to land on your feet and take less damage.
Special moves are performed by either charging in one direction - then pressing the opposite, or by inputting fast directional commands followed by a kick or punch button. If you are having trouble performing special moves, double check the commands by pressing start on the controller and going to view moves list. If you are still havng trouble - consider that the completion of a set of commands is the release of the button rather than the pressing of it. Special moves do damage even when blocked.
When your super bar is charged to the full (Charged by doing special moves or by your opponent blocking your normal moves.) you can unleash a more powerful special which will leave a shadow of your character following their moves. These do more damage and reward you with a special animation and a Super Finish if you end a round with one.
Repeatedly hitting your opponent, then grabbing them is called tick throwing. It is usually considered cheap by players - however it is not inescapable and where it was too easy to perform, the balance has been altered to make it fairer so tick throwing should be considered fair game as a tactic.
If you time a special to interrupt a move that would have hit you, you are rewarded with a reversal.
Some moves, can be cancelled by timing a special input to end on the correct frame of animation. If done correctly this can trigger combinations or simply avoid the slow wind-down of some moves where you are left vulnerable.
Okay, I'm ready to start - who should I play as? The general consensus is that Ryu is the best character to learn the basics with. Then whoever you feel like, Dhalsim is considered very technical to play as, as is Akuma. Zangief and T.Hawk require a different approach to most characters and can be hard to get to grip with. Vega is a very oddball character to play as, as is Balrog who each have their own particular game to learn.