Well what do you know so far, and what do you have so far?
Do you know that OpenVMS has a 40+ year history, was originally written for the (32 bit) VAX platform, ported to 64-bit Alpha (30+ years ago), then ported to Itanium and X86 (64 bit).
That X86 port will boot natively and you may want to ue VMware, Virtualbox or similar - within the current constraints and offeringg - visit vmssoftware.com for details.
For initial learning I recommend to just to use an Alpha or VAX emulator.
Those could run on a virtual machine, but there is no good reason.
Just run as process on whatever laptop/server your have running Windows (and some Linux options I think).
There are are several emulators out there, both free and commercial - google is your friend.
I happen to like/use FreeAXP for Alpha running under 64 bit windows - just Google.
There is no Itanium emulator.
Do you have access to the software distribution somehow?
For starters, why even bother trying to get your own system?
Just timeshare to get a feel for it.
For example SSH to decuserve.org [184.168.131.241 - ooops: 104.207.199.162 ] - ask for an account - presto!
Other timeshare options are available - and very valid to learn the basics (file system, editors, compilers,...)
Good luck!
Hein.