How to connect HC-06 with HC-08 with the HC-06 as master and HC-08 as slave?
You cannot. The HC-06 is a slave only device.
So you need to use a device as master, that is actually capable of it. I don't know, if the HC-08 can do it. Another typical bluetooth master device is the HC-05. Just like HC-06, but can also be a master.