To capture screenshots on Macs, shift + command + 4 will allow you to capture a portion of your screen
The default location to save screen shots is the Desktop. To change to a different folder, follow the instructions provided at https://discussions.apple.com/docs/DOC-9081
For example, change from teh desktop to a subfolder created in Pictures. Create the new folder first, then open Terminal. At the prompt, type
defaults write com.apple.screencapture location ~/Pictures/Screenshots/
Press Return to carry out the command.
After the work is completed and a new prompt is displayed, enter
and press Return key to run the command.
Confirmed on Mac 10.12.2