Commenting directly in the text
If the text is not too voluminous it can be handy to give comments directly in the text:

You just click on the work as shown in the figure above, write your comments and save before you go back out. Here the function "Open - Edit - Save will be used automatically (if you use Internet Explorer), so you get directly into a copy of the file that has been handed in, and can write your comments there. The actual source programme (Word, Excel, etc) starts automatically so you can write where it is appropriate in the text. For the students to be able to find your comments easily, you ought to use frames, colours, highlights etc to keep your comments apart from the actual submitted work.
When you save the file it will happen locally on your PC, but as you close the source programme/ document, this copy will be transferred to Fronter. You will get the following confirmation if this was successful:

After commenting in the document you will get two links that were not there before;

One of these is the commented on file that can be opened or downloaded, whilst the other one reverts the commented on file to the original:

With this option there is no going back!