If you don´t know something you have to learn it, no matter its name changes. Please see http://advice7.com/emotions_feelings/expression.html and http://www.self-expression.com/index.shtml to complement your interest.

I think that it can be "taught" in part. People learn how to express themselves mostly by seeing this behavior "modeled" -- someone who is self-expressed serves as a role model, others see that and think "I wonder if I could be like that?", and begin to experiment. Usually those experiments bring them up against their own limitations: concerns about what others will think, beliefs about themselves and whether or not certain kinds of expression are acceptable, etc. Someone who has a "coach" or teacher of some sort in this area has an advantage, because the teacher can see things the student can't, and speed up the process by pointing them out. Ultimately, though, the very nature of self-expression is such that you can't really get it from somebody else: it's a "bootstrap" operation -- one becomes self-expressed by giving oneself permission to be self-expressed. It's an act of autonomy: choosing to be the source of your own right to self-expression. And of course, there's no way I can let a question like this go by without a standardized Zen disclaimer: all talk about self-expression is bounded by one's definition of "self". To the degree that what is being expressed is actually ego -- the illusion of a separate self -- it isn't really Self expression with a big S at all. Even if you make it to Carnegie Hall.

I think it is much more plausible to encourage self expression than teach it. Self expression is all about having independent ideas, and sharing them with the world. If you praise and encourage those ideas, without modifying or supplanting them, you could call it "teaching" self expression, if you really wanted to, but imo it'd be a bit of a misnomer.

I believe you can teach ways and techniques, things they can make their own and change without taking away their message. Or, you can lead by example. If someone sees that you are able to express yourself, they may see that and think "How can *I* learn to express myself similarly?".