The question is not clear.
I take it SunOS 5.10 is the host, meaning you have root access to a working, physical PC running that OS right now.
What virtualization software do you have? This is a crucial piece of information. If you haven't picked one yet, I recommend VirtualBox. It's winning
the poll with nearly 50% of the vote for good reason--it works well, is easy to use and is free-of-charge.
Next, what guest OS do you want to install? Since this is a Linux forum, I'm guessing you want to install a Linux guest.