From a handout I wrote eons ago:
Show, don’t tell. Ideally, the author shows the reader everything, or nearly everything, and tells little. Yeah, yeah, you’ve heard that a million times, but what, exactly, is the difference?
These are telling:
Juan looked at himself in the mirror. His little brother pounded on the bathroom door, and Juan yelled at him to use the other bathroom. Juan wondered if his big brown eyes were sexy. His upper lip showed where his mustache would be, but something was wrong with his hair. Usually he was proud of his thick, shiny hair, but today it was lopsided, with a high, puffed-up spot on one side.
Benucci ran for his life. For the first time, he wished he’d exercised like he knew he should have. He panted for breath and felt himself slowing, not getting closer to the woods very fast. If he didn’t reach the cover of the woods, a bullet would find him.
This is showing:
Juan studied his reflection despite his little brother’s pounding on the closed door. “Use the other bathroom, Ramon!” he yelled, his eyes never leaving the glass. Good eyes, big and brown—sexy?—and the hint of a mustache-to-be, but what was wrong with his hair? Usually he had good hair, thick and shiny as his sister’s, but today one side looked like he’d hidden a Nerf football under there.
Benucci ran like he hadn’t since junior high. Why had he let himself get so soft and slow? He gasped, his lungs burning, his legs rubbery, the woods and cover still far away. Ironic, that he was about to be shot because he didn’t join the YMCA!
A lot of the difference between telling and showing is the difference between describing what can be directly observed and letting the reader inside the POV character’s thoughts. In addition, how other characters react to something tells you what that something is--when people step away from someone and wrinkle their noses, readers will know he smells.
Maryn, hoping this is some small help