naura - naurasta

I'm pretty sure this word or form doesn't exist and you should ignore it.

I'm native Finnish and this does not make any sense to me.

nauraminen + sta (mistä? = ELATIIVI) = nauramisesta

nauraminen + PARTITIIVI = nauramista

It depends on the verb which form you have to use. For example:

nauttia + ELATIIVI (mistä?)

Nautin uimisesta. = I enjoy swimming.

Nautin kirjoittamisesta. = I enjoy writing.

rakastaa + PARTITIIVI

Rakastan uimista. = I love swimming.

Rakastan kirjoittamista. = I love writing.

So, you have to know which form is used after a certain verb. Of course this takes time, but you will learn this little by little.

“Mistä” means “where from”, the -stä suffix means away from. I am not a native Finn, but this much I know.

Wow.. I thought "hey there's a Finnish question for a change", and then I read the question and had no idea how to answer it. :D

I guess it boils down to grammar study, which I can't help you with, but I can try to explain the meaning of these specific verb forms.

Naura-mista would be used in a sentence like "I can't stop laughing" -> "En voi lopettaa nauramista" or "you need to limit that laughter of yours" -> "sinun täytyy rajoittaa tuota nauramista.

Naura-sta does not make any sense. I guess it doesn't work with a verb but with a noun. There it means that something comes out of the object. "I stepped out of the car" -> "Astuin ulos autosta". "You get a lot of protein from milk" -> "maidosta saa paljon proteiinia".

Naura-misesta would mean that you get something from this action. "I get a lot of pleasure from laughter" -> "Saan paljon iloa nauramisesta"

naura - naurasta (mistä?) elatiivi

nauraminen - nauramista (mitä?) partitiivi

nauraminen - nauramisesta (mistä?) elatiivi