Free will, is the capability of agents to make one of alternative futures the present. The logic of free will has two main parts, a categorical distinction is made between all "what chooses", and all "what is chosen", referred to as the spiritual domain and the material domain respectively. This understanding in terms of two categories is named dualism.
Together with these two domains come two ways of reaching a conclusion, subjectivity and objectivity. You have to choose to identify what is in the spiritual domain, resulting in opinions (subjectivity). You have to measure to find out what is in the material domain, resulting in facts (objectivity). 
Practical understanding Edit
Look at the sky at night, and see the stars in the sky, then copy down the positions of the stars in a notebook. That is how objectivity works, copying information from nature, resulting in facts.
If you then consider that the stars could have turned out a different way than they did, perhaps that things could have turned out in such a way that those stars didn't come to be at all, then one can only reach a conclusion about what made the decision turn out the way it did by choosing the answer. This procedure is how subjectivity works, creating information yourself about what chooses instead of copying it, resulting in an opinion.
the individual Edit
The individual is who somebody is as being the owner of their decisions. By a way of choosing what emotions somebody has in their heart an opinion is formed on who somebody is.
For example, if you say somebody is a "loving" person. You reach the conclusion the other person is loving by a way of choosing the answer, expressing your own emotions with free will. The resulting opinion reflects both on who you are as being the owner of your decisions, and who the other person is as being the owner of their decisions.
Overview of the dual categories in free will Edit
|what chooses||what is chosen|
|spiritual domain||material domain|
|subjectively identified (creates information)||objectively measured (copies information)|
|God, human spirit, love, hate, self||solids, gasses, fluids, fantasy figures, mathematics|
- ↑ William of Ockham, http://www.philosophos.com/philosophical_connections/profile_050.html#ocksec2 , quote: "we can have no knowledge of an immaterial soul; nor can we prove its existence philosophically. Instead we must rely on revealed truth and faith"