picturebox question

So i have a question, i can't find anywhere!
So i'm going to write it here.
My Situation:
i have a form where a user write the coordinates of points!
Now i have a second window, where only is a picture box(but this form is first hiden)
My Question:
When i make a Line in the First Form for the second and then open the second
the picture box is just white!
Is there another Object(not the Picturebox) or have i make something wrong?

(if you haven't understood something ask me!)

thx trevex
PS sorry for bad english

You mean that when form 2 covers up form 1, all your drawing disappears?

You should either draw to a BackBuffer (a bitmap object behind the scenes, then copy that to your picturebox in its paint event), or manually do all your drawing in the paint event. If you are using complex graphics (doubtful) then backbuffering would be better. otherwise put your code for drawing things into the paint event of the picturebox.

How i can make a picture without the user notice something and how can i save a picture to the backbuffer?

Edit:
Can i reach variables from the first form in the second???
so i can make the picture in the second!?!?!