right... first of all - getting a copy of Solaris. you can download it for x86 (Intel) and SPARC here:
http://wwws.sun.com/software/solaris/binaries/get.html
The Intel version does cost $20 though (as trickykid mentioned).
You will then need to either install it onto a SPARC machine (if you can get hold of one) or pay $20 and install it onto your x86 (Intel) machine.
Once you've done this you will need some kind of howto... i don't know of any in particular, but if ur good with linux then you will find a lot of similarities in solaris as well.
http://docs.sun.com will have all the information you will ever need, although it can be quite difficult to just browse sometimes. I get most of my help on forums, such as this one.
i'm gonna plug my own site now too, as it's a useful resource:
http://unixforum.co.uk - feel free to delete the link though moderators. i'm sure u will if it's out of place