This is not an easy game to make for a beginner.
I think maybe use a 9patch object to draw lines. When player touches one dot, you spawn 9patch and as the finger moves, increase 9patch width. When the finger changes direction, spawn a second 9patch at a different angle and so on.
The tricky part will be to allow the player to leave the line unfinished, then return to it later. Or build two lines from both dots and then connect two ends together.
Also, if levels are created randomly, you need to make sure that they are solvable.
All this can be done, but the logic might be a bit complicated.