Please explain Serial.print to a dumb newbie

Yeah, heed deSilva's warning... nobody told me that and I used digital 0 and 1 as an output and input for a sensor and spent WEEKS trying to figure out why Serial.print stopped working! Talk about almost making a noob break down in frustration. To make things worse, it was the very first project I ever made on my own after doing a bunch of example projects. Man I thought I was in the wrong hobby.