How to make model's arms + weapon follow cursor?

Just like the title says. I currently have my controlling movement working just how I want it to. Now in order to proceed with shooting I first should focus on how the model should look like to determine how my script should act when firing. Currently I am using Unity’s Constructor model, but now I need to create my own model just to get the arm movements to follow how I want it to. I have an idea how to make the arms follow the cursor, by adjusting the X and Y axis rotation to follow the position of the cursor, taking on screen coordinates then using Atan to find the right angle. First I have no idea how to make a model, so I guess I need to figure that out first, but how can I make it move like the constructor model from Unity. I have heard of rigging, but still not sure what that is. I have played with C4D when in high school which I noticed while modeling it help provide a human like effect when controlling joints. I am planning on using Blender so if anyone had 3D modeling humanoids video with rigging or skeletal joint or something. Not an artist at all, but I need a model I suppose.

This is a 2.5D platform game, 3D environment with 2D physics.

This gets asked a lot. Try searching Answers for ‘lookat mouse’.

The simplest solution is using Transform.LookAt (or Quaternion.LookRotation) to make the arm point at the point in the world where the crosshair hits, often found by using a raycast using Camera.ScreenPointToRay. See the Scripting Reference for super awesome details: Unity - Scripting API: