New Lightroom guy with ? on saving corrections.

I'm new to Lightroom. How do I save corrected images.

I recently cerrected some photos and when I went to post them to facebook, they were the original photos. When I enter Lightroom, they are corrected. When I look at them in my computer files outside of Lightroom, there are the originals. How do I get Lightroom to change my originals to the corrected form? am i doing something wrong. My last photo program did this automatically!