So noob question coming. I need to draw some connecting lines on top of images but I've been struggling to do so. Everytime I draw a line (with the Pen tool) it just sits on top of the image and erases it. Can you give me a hand here? Thanks in advance!
With the pen tool you're making a shape using points, just like in Illustrator. Currently, in the top bar you can see that your shape is set to a white fill colour and grey stroke. This is why when you start to make a shape, you are seeing the white triangle on top of your image.
The solution, make a path with just a stroke colour OR use the line tool :)
Hope this helps!