how base point of bitcoin public key x , y formed n = FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364140

p = FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFE FFFFFC2F

base point of bitcoin public key x , y 

Gx = 79BE667E F9DCBBAC 55A06295 CE870B07 029BFCDB 2DCE28D9 59F2815B 16F81798

Gy = 483ADA77 26A3C465 5DA4FBFC 0E1108A8 FD17B448 A6855419 9C47D08F FB10D4B8

private key of above public key is 1

how this base point x , y formed please explain in clear and brief with some example

Thank all
They are defined by the standard. See http://www.secg.org/SEC2-Ver-1.0.pdf page 15, section 2.7.1.