How should I connect my dishwasher if the wires are yellow and blue?
Where are you located and how old is the house?

In the U.S. there are some standards for household wire color coding: http://www.angieslist.com/articles/what-do-electrical-wire-color-codes-mean.htm

If you own a multimeter, you can measure the voltage on the yellow and blue wires. Determine what the voltage is and if it's correct for the dishwasher. You will also be able to tell which wire is hot and which is neutral.

The black on the dishwasher is your hot wire, and the white is the neutral.

If you are not able to, or not comfortable testing the wires, please hire a professional to do it for you. Household electrical can be dangerous and must be done correctly.