Akkusativ is mostly used talking about action or movement from on eplace to another. Dativ is used when when there is something that is standing somewhere. 

Ich gehe ins (in das) Kino. Akkusativ

Ich bin im Kino (in dem ) Kino. Dativ

das Kino, Kino is nuetrum ( auf deutsch)

Dativ is also used in many other occasions. And even in this particular example that i gave it is possible to look at it from a different prospective.

Hope this helped.

If you have learnt Nominate, Accusative and then Dative then you should know the difference.