See the introduction to Hungarian possession for a broad description.

The biggest difference between this an owning single objects is the letter i.

First, decide how many objects are owned.

If one item is possessed, go to the single objects page.

If several items are possessed you need to check that the number of objects is qualified but not quantified. That is, if we have "some" but you don't know the exact number.

If you know the exact number, go to the single objectspage.

Then, select the owner of the object.

The owner is either I, you, he/she/it, we, you (pl), or they.

Finally, apply the relevant endings.

Owner	Charactistic ending	Endings	Examples
én	-im	-im/aim/eim	almáim	dobozaim	kezeim	házaim
te	-id	-id/aid/eid	almáid	dobozaid	kezeid	házaid
ő	-ai	-ai/ei	almái	dobozai	kezei	házai
mi	-ink	-ink/aink/eink	almáink	dobozaink	kezeink	házaink
ti	-itok	-aitok/eitek	almáitok	dobozaitok	kezeitek	házaitok
ő(k)*	-ik	-aik/eik	almáik	dobozaik	kezeik	házaik

alma = apple
doboz = box
kéz = hand, becomes kez- when endings applied
ház = house

Note how alma + aim -->  almaaim --> almáim
See the note on lengthening trailing vowels

^*  See the explanation here: single possession

There are certain nouns that take an additional -j- before the regular endings. These words, despite ending in a consonant, do not take the vowel-initial ending directly but instead take this -j- version.

There are two categories. You just have to learn which a word falls into.

Category one. The word takes the extra -j- in the third person with singular possession and in all plural possessive forms. An example is kar arm.

karom karod karja karunk karotok karjuk

karjaim karjaid karjai karjaink karjaitok karjaik

Category two. The word takes the extra -j- in the third person with singular possession. An example is barát friend.

barátom barátod barátja barátunk barátotok barátjuk

barátaim barátaid barátai barátaink barátaitok barátaik

In a way these nouns are irregular and you must simply learn them. Often a dictionary or glossary will indicate to you this fact.

The second type is very rare. Some other examples are szomszéd, ügyvéd.