i’m new to unity so please tell me how i align my model to the z-axis (forward vector)
You can’t, you need to rotate the pivot in the 3D application you made the model with.
Another way is to separate appearance from functionality. Create an empty gameobject as the root for your model, that gameobject would have all your scripts attached, then parent your model to it. This way you could just rotate your model to face any axis you need.