You have to ask yourself why did I replace the battery?  Was it doing
nothing when you turned the key?  It may be the starter.  What does your
dome light do when you hit the switch with your new Battery? Ok, first off
make dang sure you have a good connection from your new battery, that means
Cables are NOT corroded and you have a good connection and a good charge in
the Battery.  The ign. switch is used as a low voltage switch that sends
juice to another switch called a solenoid, that is a switch also but it
kicked over some heavy amperage that would fry your key switch, if you can
imagine having you battery cable hooked to it.  The soleniod transfers the
battery directly to the starter.  If you know anything about starters, you
know that you can bypass the solenoid to test your starter(dont stand in
front of a manual shift car and do this in gear) If you have a set of
jumper cables and you hook the red lead to the big post of the sarter, and
then the black lead to the engine or frame, then hook the other ends red
lead to the battery post marked posative, and the black lead to the
negative, you will envoke some sparks and if your sarter is ok the thing
will kick like a stuck pig, or if its bad you will get nothing but the
spark.  If the starter is good but the solenoid is bad, the sarter will
spin real quick and not engauge the flywheel. If everything works, then
your battery cables need replaced!

Do you have the immobilizer alarm system?