Well, it's just a grammatical case. Germans use different forms depending on the grammatical gender and the function of the a word in the sentence. Meinem is the grammatical case dativ used for masculine nouns. Ich gebe mein Geschenk und meine Küssen meinem Vater. Geschenk is singular neutral and has the function of object (that is being given) so it's accusative and you use mein. Küssen are plural and also have the function of object like Geschenk. So you use meine. Vater is masculine and is the person to whom something is given, so you use Dativ and meinem. It's very complicated since you do not have different forms in English, (nor in Dutch by the way). But it goes for far more words than 'meinxx'. The same different forms are use in words for 'the' for example: Die, der, das, den, dem. So first you have to understand all these grammatical cases in general, before an answer specific to meinem, mein, meine (and meinen, and even meines) would make sense to you. So if you have not done this, just leave it for the moment.

"Meinem" is masculine and neutral form of a possessive pronoun in "Dativ" form or being used with a "Dativ verb" e.g: Ich bin glücklich mit meinem Leben. or ich habe meinem Freund einen Brief geschrieben. "mein or meine" are used as Nominativ or Akkusativ. An example for Nominativ: Mein Leben wurde durch einen Autounfall zerstört. Example for Akkusativ: Der Autofahrer hat mein Leben zerstört. The difference between mein and meine is the gender. Mein is neutral and masculin and meine is feminine or plural.

German has 4 cases: Nominativ, Akkusativ, Dativ and Gentitiv. If you don't know what it is, you should search for lessons about these. Meinem is Dativ form of mein/meine used for Masculine and Neutral. Ex: Ich gehe ins Kino mit meinem Freund (Mit+ Dativ) Ich schenke meinem Vater ein Buch/ Der Junge gibt dem Mädchen viele Blumen (Structure: Subject does sth for somebody)

What the second poster said! It's used in the dative case. My German teacher explained it as whenever you're doing something to/for someone. Like "to/for my father" is "meinem Vater". It's a bit confusing and I'm just learning it myself, haha. There's also certain verbs that you always use the dative case with. I believe some of those are hilfen and glauben.

for neuter i think, correct?