Before cases you should know something about vowels.
There are three vowel groups in finnish;
back vowels, 'middle' or 'neutral' vowels and 'front vowels'
Back vowels include A O U Å, as they are pronounced in the back of your mounth.
Middle vowels include E and I.
And front vowels include Y Ä Ö.
A single word CAN'T have both front and back vowels there..
auto, kissa, matka, aikuinen, päivä..
then the cases!
CASES
Soo.. there are 15 of them in finnish.. In English you use prepositions. We don't. We add something to the word and voila

we'll learn three VERY important cases now.
NOMINATIVE - NOMINATIIVI
the basic form of a word.. eg. house, dog, cat, letter etc.
GENETIVE - GENETIIVI
well, it's a genetive.. as dog's, hanna's, house's..
you can do it by adding a -n to the nominative.
Examples:
House - Talo
House
's - Talo
n
Laura
Laura's - Lauran
etc.
BUT as an exception, there are the words ending with -e.. they'll get the ending -en.. as
vene - veneen
veery easy so far, isn't it
NOW how would you say "Laura's house" ??
...
If you were thinking of "Lauran talo", you're correct!
INESSIVE - INESSIIVI
Now, this is very easy.
when you want to say that something is IN something, you add -ssa or -ssä to the place.
Finland - Suomi
In Finland - Suomessa
House - Talo
In house - Talossa
Bread - Leipä
In bread - Leivässä (IRREGULAR

this is called the gradation.. or 'consonant changes'..we'll learn about this later as well )
"How do i know when to add -ssa and when to add -ssä?"
If the word has any back vowels, it's -ssa
If the word has only middle vowels, it's -ssä
If the word has any front vowels, it's -ssä
And if the word ends with -e, it'll get the ending -essä.
Vene - veneessä
btw btw, if the word you're working with has a double consonant as a last consonant (mitta, tyttö...), you'll have to DELETE the other of the consonants before adding the ending.. tyttö would become tytö--.. get it? girl's = tytön. NOT tyttön!!!
WORD ORDER
The basic word order in finnish is SVO, as in English and Chinese.
If we want to add an adjective to some SVO sentence, it'd go right after the verb.
Subject Verb Object
Laura asuu talossa
= "Laura lives in a house"
don't get confused about verbs yet..
EXERCISES
1. Put the word into genetive
- Hanna (a name)
- Koira (dog)
- Tietokone (computer)
- Mitta (measure)
2. Put the word into inessive
- Ruotsi (Sweden)
- USA (USA)
- Tietokone
- Tyttö
3. What's the nominative of the word?
- Japanissa (In Japan)
- Mitassa
- Elämän (Life's)
ANSWERS
1. Hannan, koiran, tietokoneen, mitan
2. Ruotsissa, Usassa, tietokoneessa, tytössä
3. Japani, mitta, elämä