Hello all I am new to this field I require portfolio to be submitted to the college, My course which i have chosen is Game designer,

please help me as fast as possible. 

Help you how? What exactly do you need, and from whom?

With that much information, I'll give my 2 cents:

-Make 3-4 games.

-Record gameplays.

-Make a 1 minute showreel (15-20 seconds per game) that includes cool designs you created and then make more videos explaining your process.

-Create a website and put the showreel on the frontpage so nobody can miss it.