I am knitting a scarf right now, Yeah … I am a begginner. I want to start a fresh row/line with a new colour, Can anyone of you suggest me how to do that ??? 
A video will be a great help … !!!
Just start knitting with the new color. Leave about an 8 in tail and you can weave it in later. If you feel it’s too loose at that point you can tie it loosely with the other color till it’s time to weave it in.
As always, if you need it, KH has it! Amy has a video on this under the tips videos. It is about 1/2 way down the page…
http://www.knittinghelp.com/videos/knitting-tips
Best of luck to you!