How do I unlock colored blocks

To get the yellow, red, blue and pink switches you need to find the hidden shortcuts in certain levels. The yellow switch can be found after beating the second level of the game (the left side) and then just go up and the yellow switch is there. The second switch is in the first side scroller and to get to this switch you need to enter one of the green pipes on the top and that will take you to green switch. The third is in the 3 world inside the mountain and to get that you need to start the second level (the pond water)and once you start, look for a P-switch that turn the brown blocks into coins and then grab the key and swim to the key hole and that will take you to the next block switch. The last switch is located in the woods level after the 4th castle (in my opinion this shouldn't have been so short)and you need to unlock the route inside the woods for the water level. Inside the level when you get towards the end of the level you will come to a hidden passage that may look like it's part of the level but it's a clever trick to blend in the the other rocks. Just swim through it and you will get to the hidden exit where that last switch is for the Blue blocks.