Pointers on random picking

I have a theory I'd like some help with to work out a "simple" maze generator alá Berzerk, the classic arcade game. I know "nodes" are involved, so I made a sprite object that acts as the node. I put it in a family, and placed a few copies on the map.

Now, my questions woud be: What would the command be to pick 1 of these randomly, and create a line until that line hits something?

One element of answer is the System condition "Pick random instance". scirra.com/manual/124/system-conditions

To draw a line, look examples in the How do I FAQ for Construct 2, stickied topic in this forum.

Thank you. After a lot of hard work I achieved what I needed.