You can find the terminal in "Programs/Utilities".
You can also use spotlight to search the terminal app. Just hit cmd+space and enter "terminal" (without the "") and it will be found immediately (you can also start it from there directly).
To the topic:
His question was how to install teeworlds on mac and not why there are no letters and numbers on screen. So why did you guys bring up freetype?
Well, you are kind of right, we just assumed that he did try simply downloading the teeworlds app and noticed that it did not work (and the reason for that would probably be the missing freetype). If our assumption was wrong, here is how to just install teeworlds on a mac:
1. Go to the downloads page of the teeworlds website and download the mac os x universal binary (0.6.1).
2. click on the downloaded .dmg package to open it.
3. Drag the teeworlds app to the applications folder (or to some folder inside the applications folder, if you prefer to have your stuff organized properly)