Hi, Janette. Do you literally mean translate (i.e. write the names in their Greek form), or transliterate (just write the names using Greek characters)?
If you mean the former, then the names Chris and Greg would be Χρήστος (Christos) and Γρηγόρης (Grigoris) respectively. Also, how do you pronounce 'Janette'? Is the 'j' pronounced like the 'g' in 'beige' or the 'j' in 'jam'? If not, then follow what nickel said.