How the finder works
Your rashi is the zodiac sign the Moon was in when you were born, and your nakshatra is the lunar mansion, one of 27 segments of 13°20′ each. Each nakshatra is split into four padas (charans) of 3°20′.
The finder calculates the Moon's position for your moment of birth using the standard astronomical method (Jean Meeus, Astronomical Algorithms), then converts it to the sidereal zodiac with the Lahiri ayanamsa used by Indian panchangs. The calculation runs on your own phone: nothing you type is sent anywhere.
Why the time and place matter
The Moon moves about 13° a day, so it changes nakshatra roughly once a day and sign every two and a half days. On most days the date alone gives the right nakshatra, but on the day it changes, the exact time decides. The place matters because it sets the time zone. If the finder warns that you were born near a boundary, check the time on your birth certificate.
Writing it on your biodata
Write it in the horoscope section, for example: Rashi: Kanya (Virgo) · Nakshatra: Hasta · Charan: 2. If you'll match kundlis, keep the exact time and place of birth on the biodata too. See what to write in a marriage biodata.
Rashi, nakshatra and kundli matching
Both Guna Milan (36 gunas) and Porutham start from the two people's nakshatras. Read 36 gunas explained, or get the full match in the Gun Mile Report.