Multitasking with two switches and three relays

Hi there!
Here's my case.

I have a guitaramplifier, which has two switches, one for changing channel (clean to distortion) and one for tremolo effect. They make terrible pops and I figured, if I might be able to make the poweramp silent with Nano and a relay always when changing channel or putting tremolo on or off for 100ms. The delay() is of course out of the question, but as a newbie I can't figure out how to write these multitasking programs. I have no problem with the schematic of the arrangements in my amp, just programming the Arduino.

So the situation in other words:
I have two on-off switches (kytkin1 and kytkin2) (finnish, by the way), and if I change the status of either (or both) the program should put relay3 in HIGH status for, say, 100ms, and while relay3 is on, after 25ms put relay1 or relay2 (respectively for kytkin1 or kytkin2) on HIGH status (to put the distortion ch. or tremolo on) and stay in that status until I press one of the switches, which causes again relay3 to go HIGH for 100ms and during that (after 25ms) change the ch. or trem.

I have a bit of a code written, mostly copied from others:-( It does not yet contain all the relay1 and 2 parts, just been trying to make a switch to blink Arduino's led, when changing status. Unsuccesfully. Anyone?
Edit: Wrong word button changed to correct switch

The demo Several Things at a Time illustrates the use of millis() to manage timing without blocking. It may help with understanding the technique.

...R

Thanks, though I found this more useful for my purposes : Using millis() for timing. A beginners guide