From the description in man, it looks like vmstat is the command I'd use to see the memory statistics on Solaris, but I'm not sure how to use it or read the output.
The man page says the -S K or -S M switches should display the numbers in KB or MB, but I tried both and the numbers are exactly the same.

All I really want to know is how much total memory the system has and how much free memory is available. I also tried the free command, but it's not installed.