I was starting to work with it a week ago and it's a little bit strange from the arc-user-perspective. You have to start with adding your input data for example with double-click on "vector layer". This is just an empty slot while you are creating the model. Afterwards you can add the functions. At the last function you give a name for the output. Everything without a name will be just temporary data. IMPORTAND: The function didn’t work or change if you don’t save it! Here is a nice introduction: http://www.qgis.org/en/docs/user_manual/processing/modeler.html The rest is learning by doing. Have fun and good luck!

I was starting to work with it a week ago and it's a little bit strange from the arc-user-perspective. You have to start with adding your input data for example with double-click on "vector layer". This is just an empty slot while you are creating the model. Afterwards you can add the functions. At the last function you give a name for the output. Everything without a name will be just temporary data. IMPORTAND: The function didn’t work or change if you don’t save it! Here is a nice introduction: http://docs.qgis.org/2.0/en/docs/user_manual/processing/modeler.html The rest is learning by doing. Have fun and good luck!