My main suggestion is to make a section completely dedicated to downloading ImageMagick. Try to add some screenshots showing the step of the download process. I think this would really ease the user and guide them more quickly and efficiently through your tutorial. Maybe include screenshots from the pop up menus like the License Agreement screen, but most importantly I would highly suggest adding detailed screenshots from the section labeled Select Additional Tasks. At this point of the download, I was a little confused because it was not directly stated in the tutorial or within the link that was provided to start the initial download, if the user should select or deselect capabilities of the Image Magick program. Maybe try to explain what these specific capabilities do in the program.
I really like the first two sentences in this section, I think they are straight forward and get the main points across, overall great work on the introduction. The first sentence describes that the program is independent but can still work with Git Bash Shell. Then the second sentence describes and defines ImageMagick. I think this is a strong short and detailed introduction for any lower level DIGIT student to understand and follow.
Also I thought all of the links that you provided were useful and helpful within this section.
I would bold/underline/highlight this sentence within the tutorial. When I read this for the first time I thought it was an important detail that should not be missed and should be stressed and emphasized.
I would maybe change the format of this section and create a list or display subheadings for all magick Convert and Magick Mogrify
In general I would recommend highlighting/bolding/underlining/capitalizing anything that is important and needs to stick out and or information that should be stressed or avoided so it catches the reader's attention.