Step 1: Scan the hardware way
Most multifunction printers include scan and copy features. If you have one of those but have never scanned before, check your help guide. No scanner? Wirecutter, a New York Times Co. site that recommends products, has suggestions for reliable printers and scanners.
Unlike photographic prints, slides and negatives need backlighting to properly illuminate the image when scanning. Hardware designed to handle them, like the Kodak Scanza (around $170)...