ECC curve E(Fp) y^2 = x^3 + a x + b (mod p)
a point G on the curve.
n points on the the curvie.
private key q and k, with
q*G=0 infinite; k*G=K

first question: is q == n ?
2nd : how to generate q after i choose a b p & G
enctypt and decrypt has the same compute work to do?
3rd : what different with calculate q and k
they both calculate from G, can bruteforce q and k in the same time?

Frankly, I know almost nothing about ECC. The best I can do is refer you to Certicom's ECC tutorial pages:
http://www.certicom.com/resources/ecc_tutorial/ecc_tutorial.html

finally, you replied, thanks anyway!~

I would also recommend check out this book if you can. It helped me out a lot when I was learning about ECC in my number theory class!

Implementing Elliptic Curve Cryptography
by Michael Rosing

source code, etc. available at hxxp://www.manning.com/Rosing

Certicom link has changed:

http://download.certicom.com/resources/ecc_tutorial/ecc_tutorial.html

nathan