jlliagre is virtually always right.
Also, you can usually find good step by step details at docs.sun.com. Here is a page of step by step instructions for using fssnap, including with ufsdump, on Solaris 9 --
47.Using UFS Snapshots (Tasks) (System Administration Guide: Basic Administration) - Sun Microsystems. The steps will be the same for Solaris 10, but you can, if you want, also find the section of the System Administration Guide for Solaris 10 (or 8 for that matter).