Using relay simultaneously

Using 4 channel Relays Simultaneously(3 channels are used)

My plan is to use the
1st relay on for 10mins then off for 15min

2nd relay on for an hour the off for an hour

3rd relay on for 20min then off for 5min

I dont know how to code this.

This is where we say, welcome to the forum.
then ask what you have tried ?

what you seek is called blink without delay

One of the questions is about time....

Does 'one hour' means something around 55 to 65 minutes, give or take a few minutes ? like making a cake ?
or does it mean 60:00:00 with that last micro-second being super critical ? like timing an X-Ray ?

google blink without delay to get an understanding of the concept

then read This Thread

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

Have a look at Using millis() for timing. A beginners guide if you need more explanation.