The equation should be entered as dy/dx = 0.1*y+0.23*x where instead of +0.23 you will have a different value of k.
The values Min x, Max x, Min y, Max y determine the viewing window.
The line "Add init.cond:" should have x = 0 and y = 1st digit of your SUID.
You do not have to change any other values.
The applet has two Submit buttons: one for equation and one for initial value. Press both.