Donut Ghost House-
This level is fairly simple. On the first part of the level, don't jump if you're Small/Baby Mario unless you're jumping over pits and/or collecting coins.
After that kerfuffling in what might as well be a Boo Safari, you just have to enter some doors and hit some [ ' ' ] blocks and that's it.

Vanilla Dome 1-
(For the sake of time, it'd be best if you went to Donut Plains 1 and got Cape Feathers so you have one on and have one in your inventory too.)
For the first part of the level, you just mainly have to spam Y whilst still maneuvering through the level until you reach the [ ? ] block between two yellow pipes. To get to the secret, you have to get to the Red Switch Palace via Vanilla Dome 2.

Vanilla Done 2 and Red Switch Palace-
You cannot use Yoshi in Vanilla Done 2 as the level's main focus starts with a Beanstalk Piranha Plant and Yoshi cannot climb up those.
To get to the secret Exit you have to jump off a lone [ ? ] block and then go left. There will be a P-Switch. After you've colected the P-Switch, jump on it and run to the left, jump in a 9x9 Coin Square and there will be a key, just fall down the hole to the left and there will be a hole, now you can get to the secret exit of Vanilla Done 1!

[This concludes Part Two of my Strategy Guide!]

A formatting tip, when doing a review, we know that it's full of Spoilers... The spoiler warning this isn't needed. This also makes it hard to read, so next part, leave that out, please! 

I would also highly recommend that you make your parts longer. It would give you more viz!

Welp, the post was fixed