Possesion

Here are the three most useful ways to show you own something in French.

Possesive De:

The first way is by using the preposition de with a name or a noun. The de acts in the same way an apostrophe followed by an 's' works in English to show ownership. When building a sentence, however, the de acts more like the English equivalent of 'of'. For example,

Le livre de Estelle

can be translated directly as 'The book of Estelle', but makes more sense interpreted as 'Estelle's book'.
In either case, the de is the part of the sentence that demonstrates Estelle's ownership of the book.

Adjectives:

Adjectives are used in both French and English to show an object belongs to someone. These words are used in place of 'the' (le/la/l')  and 'a' (un/une)-. For example, in the sentence 'Here is your book', the word 'the' has been replaced with the word 'your' to show the book belongs to you.

It sounds pretty simple, but it is complicated by the fact that in French there are different adjectives for gender, plural objects and for words beginning with a vowel. Take a look at the chart below.

English	Masculin/Before a Vowel	Feminine	Plural
My Your His/Her/It’s Our Your Their	Mon Ton Son Notre Votre Leur	Ma Ta Sa Notre Votre Leur	Mes Tes Ses Nos Vos Leurs

As you can see, although the words change depending on the type of object that is owned, there is a distinct pattern in the endings of the words.

To use a possesive adjective in a sentence, you need to work out the gender of the object, whether or not it is plural and if it begins with a vowel. For example, you might want to write the following sentence in French:

'My neighbours know your aunt and uncle.'

The first adjective in the sentence is 'my' and it is referring to the 'neighbours'. As vousins  is a plural, we need to find the plural equivalent of my, which is mes.

The second adjective is 'your' and is referring to the 'aunt'. The word tante is feminine and does not begin with a vowel, so we would use ta, assuming we were talking informally.

In English, we can get away with using the 'your' to refer to both aunt and uncle. In French however, we need to repeat it for each object: 'your aunt and your uncle'. In this case we would use ton before oncle because it is a masculine noun (and it also begins with a vowel).

The sentence together would read: Mes voisins connaissent ta tante et ton oncle.

Pronouns

The third way to talk about ownership is by using pronouns. In English  these are (apart from 'mine') simply possessive adjectives with an 's' added to the end.  The French versions are a little more complex. Again, there are different variations depending on the gender of the object being talked about and whether or not it is plural.

English	Masculin	Feminine	Plural
Mine Yours His/Hers/Ones Ours Yours Theirs	le mien le tien le sien le nôtre le vôtre le leur	la mienne la tienne la sienne la nôtre la vôtre la leur	les miennes/les miens les tiennes/les tiens les siennes/les siens les nôtres les vôtres les leurs

The English, we use the word 'yours' to designate both the object and the fact that it belongs to 'you'. In French, the word 'vôtre' only represents the fact that the object belongs to 'vous', and so a 'la' or 'le' is placed in front to represent the object. As you can see from the table above, the stem of the word remains the same, with only a few minor adjustments to designate gender and plurality. 

Here are some example sentences showing possession:

Tu écoutes à Ben Folds, n'est pas? Ce chanson est la sienne. 

'You listen to Ben Folds, don't you? This is his song.'

J'aime la nouvelle chanson de Regina Specktor «Ne me quitte pas». 

'I like Regina Specktor's new song, Don't Leave Me (Ne me quitte pas)'

Cette cd... c'est le tien ou le mien?

'This cd, is it yours or mine?

Mes groupes préférés sont Coldplay, The Fray, Noah and The Whale, Foals, Boy & Bear, The Shins et Phoenix. Quels sont les vôtres?

'My favourite bands are Coldplay, The Fray, Noah and The Whale, Foals, Boy & Bear, The Shins and Phoenix. What are yours?'

Sa voix est plus douce que la sienne. 

'His(or her)  voice is softer than hers(or his)'


Hope this helps you on your way to getting a grip on exactly how possesive adjectives, pronouns and prepositions work. Go out there and possess possession!