I recently solved a question correctly for which I got 1 point. What does this 1 point mean and what is the use of it and how does it affect any ranking, etc.
Rankings and ratings are affected by your performance in contests. There are 3 monthly contests on Codechef:
Long Challenge (usually starts on first Friday of the month, lasts for 10 days)
Cook-Off (second last Sunday of the month, 9:30 pm to 12:00 midnight)
Lunchtime (last Sunday of the month, 11:00 am to 2:00 pm)
You can see the upcoming contests here: http://www.codechef.com/contests
After a contest ends, the problems of the contest are added to Practice section which are for practice and do not affect ratings or rankings. What you solved was a practice problem.
No unless and until you participate any of the competitions released by codechef your ratings and rankings will not change. Also ranking are affected only by participating in either Long Contest, Short contest or Lunch Time.
Ok, thank you for the information.