where do you get the colourfull boots in runescape?

The boots I think you are talking about are a reward from the stronghold of security. To get them, climb down the hole in the middle of barbarian village (or Gunnar's Ground or whatever they are calling it now). There are 4 floors. You have to make your way to the maze to the reward room. The first 3 floors have cash rewards and unlock emotes. The fourth floor gives you a choice of either fighting or rainbow boots. The rainbow boots are the ones I think you are talking about. If you are low level (like less than 50) than bring food and armor. The monsters on the last couple floors are aggressive and can do damage.