Ruslan, glad you finally got the boat rigged and sailing...major step forward! Regarding your race result, if you were competing against an experienced fleet, the difference in skill will show more in light wind than heavier winds.
Did you have tell tales on your sails? Do you and your crew constantly watch them and adjust the sails? What settings did you change from the upwind leg to the downwind leg (main traveler? jib leads? mast rotator? downhaul?) Considering the light winds, did you have the sail too flat? (too much outhaul/downhaul, too little mast rotation, too much mainsheet / jibsheet tension? A common mistake of novice sailors is that they think "the hard I pull, the faster I'll go").Where were you both positioned on the boat (crew should be forward of sidestay, you right next to crew). How smooth are your manoevers, do you and your crew have a trained tacking/gybing routine?

Ending last in your first race is not embarassing, even if it's against H16's...If you are just starting to race cats, you're looking forward to a learning curve many years - which makes this just such a great sport...Talk to people, keep on racing and go out training your manoevers...And come on down to our club some day for a race...