Uploading a photo online can sometimes be a complicated process. If you do not have your own server to host image, here are a few easier options.
If you are able to upload to your images to Google Drive, you can create shareable links that the CSV import tool will process. See the recording below for a demonstration on how to get the link copied to your clipboard:
The CSV import tool can also process Dropbox links. To get a Dropbox link for an image:
Copy your image to the Dropbox folder on your computer
Right click on the image in your Dropbox folder
Click "Copy Dropbox Link". The link is now on your clipboard!
ImgBB can also be used to host a photo:
Go to https://imgbb.com/
Upload your photo
View the share URL that gives you
Right click on the image
Click "Copy Image Address"