my gilera runner vx125 is over heating?

recently a cream like liquid came out off the top of my coolant tank i fought it was a bit odd so i took the tank of and looked inside to find big clogges of the cream like liquid so i cleamed it out but my bike is still over heating i was woundering if anybody could tell me what is supposed to go into the liquid coolant system and how to stop my bike overheating thanks