About how important the composition in photography, probably, almost everyone knows.
And the main compositional elements are lines and frames. It is they that allow you to control the viewer's view, guide him and not let him "leave" the frame.
Lines help to structure the space in the frame and "point" to important elements. And the frames create a complete composition and make the picture more voluminous and multifaceted.
I will give some examples from a wedding photo.
Here, one way or another, any composition should be built around the groom and the bride and bring the viewer's attention to them. Therefore, all the lines will point to the pair and the frames will not let the attention dissipate.
If you work indoors, then as a framework, door and window openings may well act, and guide lines will help create interior elements or furniture.
It turns out like this:
here, as a frame, ajar doors are used, and the guides are decorative slats on them. The main thing is to calculate the angle of opening the door. 
Here, as a frame, a doorway worked (yes, it's a very beautiful old mansion). And in order to properly frame the frame, I had to climb onto a chair and shoot on the arms stretched upwards. Only this allowed to capture a part of this portal, which became a frame.
Well, the lines formed by themselves because of the geometry of the room. 
In general, a very simple example. Here, the light helps to emphasize the pair. but in addition, and the line on the wall, formed by tiles. To strengthen and emphasize them had to bring the camera close to the wall. The same technique allowed to include in the frame a reflection in the tile and make it a little more picturesque. And the frame turned out of itself from the window opening..jpg)