How do I know which ROM I have ? do I need something newer to run WB 3.1 ?
You were right. The hand thing shows which version ROM you have and the corresponding Workbench is what you can use with it.
You need Kickstart ROM 3.1 to run WB 3.1, I'm not sure what other specs it requires, I imagine some more RAM.
You can get bundled ROMs and OS's (WB) at
Eyetech