New to SOA?
By Mark Wilcox - CTO - Oracle Consulting Security-Oracle on Mar 24, 2008
I don't quite remember how I found this blog link but it's a good introduction to all of the components that make up Oracle SOA and help get you started.
And if you are doing anything with Web Services - make sure you have SOAPUI in your toolkit. There isn't a faster way that I know of to test out the services.