This is indeed basic. Half the article explains public key cryptography, the other gives a basic overview that omits key details, such as the purpose of reflection, and how the curve can get combined with finite fields in practical applications (although point 2 does partly address this aspect). Not a bad way to get a general intuition of the algorithm, but not overly useful, either.
You "wrap around" because you're using a finite field. As far as I understand, the finite field of the scalars allows you to have an inverse for the multiplication, and the finite field of the points is there to make the calculation easier.