What am I supposed to do on the first scene?

There's really no way to know what to do here -- all you can do is try
things that make a bit of sense and hope that something works.

Start by looking for something that looks a bit loose.

Like one of the horns on the skull.  It will occasionally shake in the wind.

It might take brute force to get it.

Have Warrior punch the right half of the archway and the horn will fall.

Why not try using what you just got?

Have Technician pick up the horn and blow through it.

Look!  A stick just fell on the ground.