plz tell me the amount of thrust needed for a plane that is 450 gms m a beginner plz help

Welcome to the forum

Such questions have been answered many times before, just searching for the word "thrust" gives multiple threads, like this :

http://www.rcindia.org/electric-power/which-power-system-would-you-suggest/

Please spend at least an hour searching and reading, and if you still have doubts, please ask.  The more you read, the more money you save !

In addition what type of plane you plan to make also matters about the power system..... Pusher or puller .... Acrobatics or simple glider.....etc

For a beginner plane..the motor wattage is 50 to 75 watts per pound..approx.500g.