Just to be clear, we are not talking about the frame the print goes into, but "framing" your subject with something in the environment. The frame is a part of the scene, so it tells a bigger story and places your subject in context. It also suggests things about the image.
Simple framing would be doorways or windows. This creates a portal that takes the viewer into the world beyond, a suggestion of something being possible.
By being dark it adds drama, possibly danger, or suspense to your image. If it's bright beyond your subject, it lends a heavenly, divine sense to the subject.
The lighter the frame, the more delicate and happy the image will feel. It creates a desire in the viewer to go through the frame and join them, and be part of the joy. You create the emotional trick of the viewer joining the joy by the desire to go through the frame.
The frame can be in front or behind your subject and it does not even need to be complete for it to work as a frame. The mind completes things when it sees the suggestion of the shape. So a subject can be seen through a gap in a row of surfboards or, in the case of our winter, snow skis.
Here are some tricks to framing:
Don't skimp; pull back so you can see what the frame is.Keep it square. Frames usually have a geometric shape, so you have to be careful that the lines are level.You subject can "fill" the frame, or be small in the frame. Make the choice with purpose, each approach gives a different message to the viewer.In most cases the frame should not be so dark as to have no detail, or so bright it is washed out.Be creative. To be a frame you just need some space around the subject on the sides. You could "frame" a child by having them between adults but with some space so they are a little isolated and the adults are cropped out.The "frame" does not need to be in focus, conversely the subject does not need to be in focus (in this case the frame should be, though.)The "frame" can be artificial. You could hold up a fuzzy heart and shoot an embracing couple through it.
Once you get the hang of framing things you will be well on your way to creating powerful story telling images.