You can change some values as default you can also do keep a value for next use in same session. I wont go into that now but its easy.
Change to suit colored values, the 5 4 is 5 digits max so if need more say 8 7 instead for text may need like 21 20. Each can be a different size.
(setq ans (AH:getvalsm (list "Enter Values" "X" 5 4 "100" "X1" 5 4 "50" "X2" 5 4 "50" "Y " 5 4 "100" "Y1 " 5 4 "50" "Y2 " 5 4 "50" "Rad" 5 4 "10" )))
The ans returned is a list of strings so use Atof or Atoi for numbers.
I matched your way of doing x x1 x2 etc
Re learning no quick way other than keep looking at tasks like this. Start simple learn about stuff like polar for working out pts, I often draw on a piece of paper the point numbers as I code so dont lose track.
A beginner big hint work angles in radians, aunits 3, 90 = (/ pi 2.0) and the nasty Autocad is counter clockwise for angles, but you get used to it.
Just post another request then people here will help you to learn. I would look at a custom menu next adding what you download or write much easier than using appload.