MotorIlliterate

Hows it going peoples, im in a spot of bother I brought a dt200 a year ago this was ment to be my 1st bike ever i used it once ran perfect all day took it home and for the last 6 months it hasnt been going it has compression and new spark plugg with spark but i cleaned out the carb and there was a ball of green paint like substance in the carb. After i cleaned it out with my tooth brush i drained the fuel tank and gave it new fuel, it fired after 2 kicks ran i turned it off after about 5 minutes and it wouldnt fire again. It has now been 3 months later ive replaced sharp plugs again, drained the tank again but havent checked the carb yet. Does anyone have any suggestions to how i can fix this problem and to what the ball of green substance i found was. Any feed back will be a great help Yours sincerly Im Clueless