If you have used SORTIE before, you're in luck. You can probably start doing runs right away. The new version of SORTIE was designed to be backwards compatible; your old files should load and run.
Before you do a run, you may want to familiarize yourself with what's new. First, read about behaviors. They replace submodels. When before you might choose the "BC juvenile growth" submodel, for instance, now you will choose a growth behavior. All submodels from the old model have been translated to behaviors in the new model. They may have been slightly generalized and given different names, but when you read the documentation on the individual behaviors you should be able to find the ones you want.
Then, read about the new parameter files. You can load an old parameter file using the File menu, and then this topic will tell you how to modify it. Once you've done that, you can save it to create your first new-format parameter file.
Read about your output options with the topics on summary output files and detailed output files.