In the original Colonization, you see a screen with a large bubbling spring in a jungle and the title "Fountain of Youth", and when you click on that you return to the map and see a superimposed message box saying "You have discovered a Fountain of Youth! Rumors fly in Europe! Immigrants line the docks to seek perpetual youth in the New World!". The box offers a choice of three immigrants in the same style as you get when clicking "Recruit" in Europe, saying "Which of the following individuals shall we recruit?". Choose one of the three offered. You choose eight altogether. If you are lucky, there will be no servants or criminals offered.
In FreeCol, at least by version 0.9.5, you get eight but get no choice, and they may include servants and/or criminals. After getting the good news you may choose "Display" to be taken straight to the Europe screen (though it may be wiser to move quickly to save the game in case of a power failure!) and see who's there.