Most photo printers operate online - whether the sites like Shutterfly, or even Walmart and Costco - you just need to go to the website of your preferred provider, and follow instructions. Usually, you need an online account, then there's a spot that allows you to click to upload the desired photos.
One thing you may want to make sure of - what size/resolution were the photos that were e-mailed to you? If they're really tiny embedded photos just for you to view - they may not print well at all - if they're the larger, or even full size original shots, then they should be plenty to print. If you right-click on the photo and go to 'properties' you should be able to see the dimensions of the photo that was e-mailed to you. If it's something smaller such as '800x600', '1024x768', etc., then the resolution may be too low for a print, even a small 4x6" print. You want to see ideally something in the 2500x1875 or larger range for a nice looking 4x6" print and a reasonably clean 8x10" print. The larger the resolution, the better the results with larger prints. When you see cameras or phones list a 'megapixel' count, that is the same as multiplying the photo dimensions divided by 1 million...aka, 2500 times 1875 would be 4,687,500, divided by 1,000,000 equals 4.6 megapixels (MP). A 24 MP camera delivers photos that are 6,000 x 4,000, aka 24,000,000 pixels.