how can i do weight lose.

me sara..my age is 29 and weight is 78.i m too much worried abt it...already i tryed very much to reduce weight but not get effective result...aftr 2 or 3 month i lose only 2 or 3kg due to hard work like ful diet means all day i ate little then 2 or 3kg...walk and exercise.....i m very worried abt it....plz tell me a effective diet plan and activities...me waiting your reply.