The Upgrading Process is stupidly easy. The process is well documented for each release and is available after the release of binary packages and when install images are out but before going any further, please read the OpenBSD 6.2 new features for the list of changes and improvements.
The process is split into two separate processes:
I choose Upgrading via a bootable media since it is the highly recommended way:
$curl -o install62.fs https://openbsd.mirror.netelligent.ca/pub/OpenBSD/6.2/amd64/install62.fs
Writing the image to the USB stick was a matter of executing dd command (as always):
$ sysctl hw.disknames
hw.disknames=sd0:da0bedc25009303c,cd0:,sd1:9e5b01f8dc3ea3f3
$ doas dd if=install62.fs of=/dev/rsd1c bs=1m
Again, if you're unfamiliar with anything like OpenBSD way of dealing with storage devices and other things, please consider reading the entire FAQ. It really pays off, I promise ;-)
Now the next move is follow the pre-upgrade which I actually forgot. For my currect setup, it was only to manually remove the man pages to avoid having old manpages in the new system after successfull upgrade:
$ doas rm -rf /usr/share/man/
Now, Just rebooted the machine and booted from the USB stick and Press (U)pgrade and that was it. After confirming the keyboard layout and my laptop's primary disk where my OpenBSD installation resides, the process of Upgrading The Base System was done. After completion and rebooting the machine, the first thing the new OS did was retrieving the newer firmwares which I skipped since at the time, I had no (reliable) Internet connection, but don't worry, you can do it later:
$ uname -a
OpenBSD localhost.lenovo 6.2 GENERIC.MP#134 amd64
$ doas fw_update
Now, it's time to update the binary packages since their dependencies on the base system has just been upgraded. But that was just one command away:
$ doas pkg_add -u
That was it. Hope to write more about OpenBSD in the near future.