I am trying to follow these instructions but not succeeding in what they are supposed to instruct. Can somebody please shed light on how to do this?
⌘ cmd + ⇧ shift + 3 will screenshot the entire screen and save it to your desktop. (You should hear a camera sound when you do this.)
⌘ cmd + ⇧ shift + 4 will give you crosshairs to use to select an area for copying. Move the crosshairs to the location that you want to copy and click the upper left, dragging the crosshairs to the lower right of the area you want. When you release, you will hear the same camera sound, and the screenshot will save to your desktop.
Also, ⌘ cmd + ⇧ shift + 4, then Space, then clicking any window will save that window to a screenshot.
To change the location of the saved screenshot, launch Terminal and use the following command:
defaults write com.apple.screencapture location /path/ && killall -HUP SystemUIServer
Make sure you change
/path/ to be the location where you want your screenshots to go.
If you take screenshots to the clipboard, you can paste them into the message and not deal with the intermediate file. Use ⌘ cmd control ⇧ shift 4 to go to clipboard. (Add control to the other shortcut.)
Note that creating the file is more reliable than pasting for cross-platform messages.