I am trying to wire a pull chain switch to a fluoresent light. From the ballast there is a Black, White, on one side and a red wire and a blue wire on same side. On the other side,
There are two reds and two blues. How do I connect the pull chain switch?

First off, BE CAREFUL!! There is lethal voltage in a fluorescent ballast.
MAKE SURE power is off to the WHOLE fixture before beginning.

The switch will have two black wires. The power coming in goes to one black, the other black goes to the black from the ballast. Everything else stays the same.