There should be a print screen button on your keyboard. Usually on the top right somewhere. Press that when you are looking at your team, or whatever you want to create a picture of.
Then open a program like paint or photoshop and create a new blank file. If you go to edit you should have the option to paste. Press that and an image of the team, or whatever was on the screen when you pressed print screen, should appear. Save it and then upload it to a website like photobucket.com. You'll then get an url for the picture that you can include in posts