This is a suggestion not "forum law", but it is always best to provide as many screen shots as possible. The reason for this #1 would be language barriers. #2 not everyone knows the "proper" names of the different window "widgets" or items things like a context menu. so images go a long way. if you press alt + printscreen on your keyboard windows will do a screen capture of the application that is in focus, the one that is in the foreground.
It sends the capture to your clipboard so you will have to use some kind of an editor to paste the image into for being able to save it. now i personally will at that time do any re-sizing but will also indicate on the image via an arrow or a circle and identify the exact piece i am talking about. and it's best to provide a before the setting change and after the setting change. I do like using paint.net it is free and has nice little lines you can use to paint and you can change the ends of the line to say an arrow. it's free and there are lots of plugins made for it. but it also has nice blurring or pixelating features that are useful for making any sensitive information unviewable.
paint.net can be downloaded from here
or if you have the ability to do so a video is always helpful as well.
If you want to do a video I personally use a Screen Recorder Utility that had an article written about it in TechNet Magazine in the Utility Spotlight section.
This utility uses Windows Media Encoder 9 and is really simple to use. it will only make wmv but converts can be found all over the internet. due to the extremely high resolutions of monitors these days. a video file can get really really large. so resize the video to 640 X 480 please, this utility also allows you to specify just a single window to record or the whole desktop. and with or without audio. it uses Windows Media Encoder 9 and if you do not have it installed it will download it for you.
I have attached the utility as it is only 22 meg. If you have an issue with the utility doing a Not Responding error. I have also attached a windows HotFix for Windows Media Encoder 9
Now the Forum does have locks set in place for what you can attach and also for size and # of files. These Limits are as follows.
10 meg per file, and 10 files per post. and it will not allow for uploading of videos.
if you are going to be outside of those permissions send me a PM and I will temporarily change your permissions for this forum to allow you to put up the images and or / movie.
I do not want to change the permissions for this Thread on a perm basis due to load times of the pages if someone gets a little out of hand. if it's a movie you post and it is not 640 X 480 i will re-mux and re-size the video to 640 X 480 trying to attain the best possible quality for the smallest size and I will remake the attachment for that post. Now i do prefer if you do this yourself. but if you do not know how end me a PM and ask. if you do not have the time to learn i will be more then happy to do it for you.
Videos would be the best choice because you really won't get many user errors that way. just remember that some people might not be as computer savvy as you so move slow and also provide some time for the user to click the pause button to go and perform that operation. don't put to many steps together as it is hard to remember and the user will have to click back and forth and rewind and listen/watch again. and this does get extremely irritating. by keeping the steps small and giving that pause to pause is probably the single most helpful thing to do when making an instructional video. If you have the means to do captions then by all means add them.