download pictures to my phone from computer

Download iCloud for Windows - Apple Support

More than just your photos can sync.

The easiest way, without having to use programs or cables is from your PC, sign in with your Apple ID here: https://www.icloud.com

Open Photos on the website and drag the image you want over there. After you can find the photo in the Photo app on your iPhone - remember to turn on iCloud Photo. Settings -> Photos

You can also open iCloud Drive and drag the file in there, then you can find the image in the Files app on your iPhone.