A concise introduction to Asymptote is given here.
For a more thorough introduction, see the excellent Asymptote
tutorial written by Charles Staats:
https://asymptote.sourceforge.io/asymptote_tutorial.pdf
Another Asymptote tutorial is available as a wiki,
with images rendered by an online Asymptote engine:
https://www.artofproblemsolving.com/wiki/?title=Asymptote_(Vector_Graphics_Language)