A character remembers an action that happened in that character's past, and you (the author) want to recount it within the story.
You continue on with your story, using past tense as before.
Here's a rather overwrought example off the top of my head. Let me know if it's clear for you.
She sat down at her desk and opened the drawer. The ivory invitation stared her right in the face, its fancy letters mocking her like the echo of his voice.
“After all this time you're finally invited,” he had said. “I bet you won't go.” He had slumped onto the sofa, smirking, and daring her to fight.
She hadn’t looked at him. Instead she gazed out the window at the roses. They were just about to bloom. She stared hard as if the bursting buds were the only thing that mattered in the world.
“I don’t know.”
He had laughed. Before he had the chance to say anything else, she’d had him thrown out.David Deen, the Research King, recommends the following websites (just click on the link):
She picked up the invitation and dropped it into the wastebasket. There, that's better. Much better.
Writing Genre Fiction: A guide to Craft
Past Perfection at Writer's Relief Blog
Fantasy Fiction Cliche's to Avoid