Automatic Transmissions Servi

Hello atodos of this forum, I would like someone to tell me how to do the service to the automatic transmission of my Chevrolet Blazer Tahoe 4x4 1993, its oil smells old and takes time to change the marches, I want to replace oil and filter and purge the converter circuit. Please help me how to do it, my thanks to those who give me an answer, thanks "" ""