First things first
As an old logger told me when I was starting out, "before you can sharpen a chain you need to know what a sharp chain looks like. Otherwise all you're doing is randomly removing metal." That said what you need is a properly hand filed chain that you can use as an instructional aid. No tool will produce the proper end result(s) if you don't have a clue as to what they are. Sounds simple but many people's hand filed chains I've seen appear to have been filed via the hit or miss method.
"Sharpening" a chain involves a process generating two results. First is creating a keen edge(s) that pierce and slice into the wood. The second is to develop the cutter tooth geometry, including the rakers, that allow the edge to do its job efficiently. Think about it, you can have perfect angles but if the edge is folded over, no chips. The same applies, superb edge, but lousy geometry, again no chips or a cutting edge that dulls very quickly.
As you're starting out I recommend putting the saw in a sturdy vice, look at the sample chain, and start filing a few strokes at a time. Stop, re-examine what you've done with the sample, correct if need and proceed again. Learning takes time, patience is key. A jig such as the Granberg will help maintain geometry tooth to tooth, but you still need to get the proper file depth and raker height. For freehand, I use one of the Oregon or Stihl file holders previously mentioned. Not trying to set angles etc. with it, but it just makes holding the file so much more comfortable with all the arthritis I've developed in my hands over the years.
In short, take your time, think about what you're doing, practice and you'll get there. Once you have the basics then you can move on to sharpening based upon the type of wood you're cutting or will be cutting.
Take Care