The following topics are all available in this new member article (useful for all members). At the top of the article you may click on the "Show Me" section for a step-by-step 11 minute YouTube video (you may skip ahead with the right arrow at bottom of video) .
You may scroll down to the article's following topics or select the individual item here for specific help:
RENEW INSTRUCTIONS:
Resizing Images V2.pdf (WIndows or Mac Preview)
How to properly size an image in Photoshop.pdf (Photoshop)