If you replaced the batteries correctly, the smartkey will program itself once you insert it into the ignition.

Proper installation of the batteries requires that they both face each other (flat side looking out on both). After replacing mine, I found this configuration sort've odd but that's how it works.

Good Luck

__________________
-Paul-
'01 E430, Sport 72,000 mi
'98 C280, 126,500 mi