Your commentary can take many forms.  Which form you employ depends on the evidence and the points you are trying to make.  The commentary may be as follows:

• Explaining or clarifying a point
• Inferring from facts
• Drawing own conclusions
• Extrapolating from parallel contexts
• Showing implications
• Showing effects of a problem/issue
• Showing causes of a problem/issue
• Reiterating pertinent information or points
• Linking information to larger issue and/or main thesis
• Comparing unfamiliar issue to a familiar one to increase understanding
• Contrasting/juxtaposing issues to sharpen argument by making distinctions clearer
• Others