fender blues junior mod

How I can compress the sound Blues Junior?
I use a fender blues junior with a telecaster american made .. I just want the audio compressed but I like the triple high brightness and high amplifier volume before a good rock tone. I do not want to use a pedal sompressor who was waiting to put a mod on the amplifier.
my understanding of compression is to limit the peak signal in general? idk. I have a Start with an adjustable phase switch. I've marked then I like and give it that sound compressed. With a TV (and that to this day) you should be able to get a working installation that was a push-pull knob, I do not I know. My start has a toggle switch.
Modified Fender Blues Jr. tube amp