how do I make a NPC got to a random place randomly?

I am trying to make an npc walk randomly when the game starts but it wont work none of the objects work please help!! I looked on the internet and all scripts were not working! I put it in a normal script my script so far: I also have tried putting walk to part to a certain part but it wont work

blue = math.random (1,5)
while true do 
script.parent.CFrame = CFrame.new (blue,red,green)

I expect it to walk to a random point in the terrain