Changing brakes on a 2003 Aztec?
That's a really loaded question for a short response. Most modern cars use electronic antilock systems that can be damaged if simple pad replacements are not done correctly. If you don't know how to do this type of job, you are probably safer and better off paying a professional to do it for you. Brakes are nothing to get wrong... For help in finding a good mechanic, take a look at the related links for some tips that may help.