Hello guys im pretty new with 3D and i need some help with my renders because i dont actually know how to pose the models, or which kind of lightning is better, is there a tutorial that could help me with that? 
My renders seems pretty bad so i need to improve. Please help me.
Lighting, scene composition, camera angles and compositing/Post processing will make a huge difference in your renders.
If you are a CGC member , then you may find these courses helpful :
https://cgcookie.com/course/introduction-to-rendering
https://cgcookie.com/course/fundamentals-of-lighting
https://cgcookie.com/course/fundamentals-of-compositing
At first glance, the scene seems really flat. Instead those objects should pop out of the screen. The tutorials mentioned above should cover you! Nice modeling job!