How do you find individual after collision momentum of 2 objects?

There isn't a quick answer to that, it a whole topic in its own right.

How do you find individual after collision momentum of 2 objects? Not the total momentum because that equals the initial total momentum. I mean the individual momentums.

depends on what kind of collision, and what other info you have. You know the sum of the initial momentum has to equal the sum of the final momentum, for example. 

for an elastic collision, you can use this:

Elastic collisions

v is velocity after the collision, u before

v₁ = (u₁(m₁–m₂) + 2m₂u₂) / (m₁ + m₂)

v₂ = (u₂(m₂–m₁) + 2m₁u₁) / (m₁ + m₂)