How to stop Ken crossing you up as Blanka

There are several ways of doing charges.

Easiest, of course, is to just hold back/down and let it rip after 2 seconds.

The harder way, is to be charging while doing a jump or attack combination and then letting it rip at the end, which is what you are supposed to do with charge type characters, such as guile and blanka. Do not be ultra defensive! Keep them guessing with your pokes, and if they make a mistake, combo into it.

While you will never be able to spam as fast as Ryu or Sagat, there is a way to minimize your charge time via buffering, see this video for a good explanation.

Short description for those who can't, or doesn't want to watch the video:

Instead of doing a back-2seconds-forward sonic boom, you do a back-2seconds-forward-back sonic boom, this allows you to be charging for your next sonic boom while your current sonic boom animation kicks off, and using this technique will allow you to add multiple sonic booms into your combos more effectively.

To throw, you press the light punch and light kick buttons simultaneously. This is a universal command for every character. By default, these are the Y and B buttons on the 3DS. You can also assign the buttons on the touch screen to this shortcut in the options menu.

If you are next to your opponent, your character will perform the throw. You can also throw the opponent forward or backward by pressing that direction when you perform the throw (i.e. back + LP + LK).

If your opponent is not in range, jumps away before you throw, or is otherwise unthrowable, your throw will "whiff", and your character will be vulnerable for a short time while the throw miss animation plays. Your opponent can also cancel your throw, or "tech", by pressing throw himself within a few frames after you grab him.

Some characters also have additional special throws, sometimes called "command throws". For example, Abel has Tornado Throw, done by doing a half circle back + punch. These would be listed in the command list and can also be assigned to the touch screen buttons.