If you use GEMIS on your computer, the F1 key activates the context-sensitive help function which offers explanations of the model use.
You can get a brief explanation on themes and terms of GEMIS in the Glossary, and there are also answers to FAQ.
Furthermore, the model documentation and Online-Help are separately available here.
Practical introductions to GEMIS applications are so-called Tours - they explain in a step-by-step fashion how to use the model for certain tasks, and how to access certain features. We are working on the English versions of the Tours and have prepared preliminary translations of the first four which you can download now - we'd appreciate your comments on those !