How do I get world 4 n 7 how do I get world 4 n 7 because I played the..

To get to world 4, you complete the big castle in world 2 with mini (the smaller-than-small) mario.
To get to world 7, you do the same but with the big castle in world 5.

You need to beat level 2 final boss as mini mario. The same goes for the final boss of level 5.

Don't worry, it's easy.
To unlock world 4: you must defeat the world 2 boss level (the big castle) with a mini mushroom. You do not have to defeat the "whole" level with a mini but you do need to defeat the boss with it.
Here's how to do that the simplest way: play W1-1, make sure you beat this level with a fire (you will need it to get through the castle in world 2) now jump on the flag exactly with the time saying "333" this will unlock a red mushroom house go into the house and click the pause button when the box is at a flower, then double click "A" really fast. You will gain a mini mushroom! (if not you messed up, go back and start over) now go through the entire castle level of world 2 ( without using your mini mushroom - this may take a few tries) right before you go into the double doors use your mini, go inside and defeat the boss by pounding down on his head when hes short
For world 7 : Do the same, but this time you must defeat world five boss with a mini mushroom
GOODLUCK ;)