Could you maybe help me out? I'm making one and i need to know more about them...... so could you maybe do a little explaining?

At your service, Naveion.
The kuijins were originally created by the user Exalok, who isn't active anymore (and I still need to delete his/her/its account). So, anyways:

Why they're seperated from humans:
Humans and Kuijins an ongoing feud. The reason isn't actually sure (Exalok's going to find out someday). Whenever the humans discover Kuijins, the humans attack them, driving them out of their territory, or just trying to kill them. (If the Kuijins escape, well, too bad)
But, even with that, Kuijins can reproduce with humans. But the children very rarely survive, because of genetic anomalies. The ones that do have usually lots of problems (prone to getting sick, tiny bones, etc).

Description of Kuijin powers:
When Kuijins are born (KuijinxKuijin, or even KuijinxHuman), they're given a soul animal and their basic form resembles that soul animal. The animal can be insect, mammal, etc. Thyere can also be "mythical creatures", as mythical creatures are animals, originally. But it can't be true mythical creatures, such as, if the kuijin had a dragon soul animal, it wouldn't be able to breathe fire (lololgodmod).
Their soul animal is a mixture of their parents' soul animals, or else something which closely resembles the soul animal of one of the parents. When a Kuijin transforms into their soul animal, their mass STAYS THE SAME. So, basically, the size changes, proportionate to the mass of the transformer. Their weight always stays the same, not any more or any less. For example, a bird kuijin, since its got hollow bones and feathers, would appear much smaller if it transforms into a human, which has whole bones, and a generally compact physique. On their mating habits, usually kuijin couples are made of two kuijins whose soul animals are similar. (FalconxSparrow, FalconxEagle, TigerxLion, etc). Since they're both kuijin, there is no particular anomaly that will appear in the child, except if it's of course in the genes of one of the kuijins. It is possible for two kuijins with very different soul animals to form a mating pair, but it's usually seen very badly in the kuijin community. The children which result from such a pairing are called Hybrids.
There's a legend that says that all the original kuijins had normal animals, but since there is practically only one kuijin per species, sometimes two but it is rare, they had to mate with different species, and that gave kuijins with soul animals with a mixture of other animals, and that gives the inexact animals which kuijins have in the present day.


Have any more questions?

I have a few more questions the first is about naming. Is this something they would be named Alteris Heriphem Lonok, or does it mater? Should I put something under abilities like how he can morph? Oh and thanks for the help.

And do they have schooling or is it possible for them to hide among humans? I'll stop asking questions now.

Sorry, but Copynpaste is absent most of the weekends, he should be back this evening.

Okay, good questions thar:

Name doesn't matter/ For all I care, they could be named wjihsfiyuji, put it has to be pronounciable and cool. So your name works.
All Kuijins basically morph the same way, depending on their soul animal. The parts they cannot totally morph shall morph faster, into the creature. But they cannot 'Half-morph'. They can either try to go completely human (still having animal traits, alas) or completely animal.
The Kuijins are taught by their eldars, or else they go to school, hiding all their animal features. They can hide from humans, in condition to be quite covered.
Example: Ahrach the eagle kuijin, has long black clothing to hide his feathered forearms and his bird-like legs.

So are all kuijin hated by humans, oh and that's a last question, maybe. I'm sorry, I just stink at making characters.

Most humans hate kuijins, yes, but the kuijins are a forgotten race: They've not been found out in public for many, many years. The humans only hate kuijins, because they seem like a consciousness that would be able to decimate their overwhelming destruction.

Can I go as far as to give him cat eyes ? Oh and do you mind I'm not totally doing what you explained right there.

Cat eyes are perfect, yes.
Note:--
Keep in mind that if the Kuijin isn't a good morpher, even more animal-like features are obviously apparent on the human form of the Kuijin.