You always draw the last bullet created. Go through each of them in a for each loop instead.
Also you don't need this
Maybe you should change
to
As it could confuse the compiler
For b.bullet = Each bullet DrawImage bullet, b\x, b\y Next
Also you don't need this
If bulleton
Maybe you should change
bullet.bullet = New bullet bullet\x = player\x - 10 bullet\y = player\y - 10
to
b.bullet = New bullet b\x = player\x - 10 b\y = player\y - 10
As it could confuse the compiler