A great place to start is
https://wiki.lazarus.freepascal.org/Developing_with_GraphicsIn your program, you will declare something like
TraceVu: TBitMap
and then at the appropriate point in your code do something like
TraceVu.Canvas.Pixels[x,y] := cl.Red;
which will draw one red pixel at point [x,y] on the canvas.
Work a few of the examples in the wiki and you'll be up the learning curve in no time. TChart is amazing, but you can't beat handling your own pixels for the ultimate in presentation flexibility.