Summarize:

Go to https://wetransfer.com in your computer's web browser. This blue button is in the lower-left side of the page. Doing so opens the transfer form. It's at the top of the transfer form. A window will open. Go to the location of a file that you want to send, then click the file to select it.  To select multiple files at once, hold down Ctrl (Windows) or ⌘ Command (Mac) while clicking individual files. You can select up to 2 gigabytes' worth of files. Fill out the following fields:   Email to - Enter up to 20 separate recipient email addresses. Be sure to press space between email addresses.  Your email - Enter the email address from which you want to send this file. It's a blue button at the bottom of the form. Doing so will cause the file to upload, after which point it will automatically send to the "Email to" email address(es). To download the file, you or your recipient must open the email, click Get your files, and click Download.
Open WeTransfer. Click I agree. Click Add your files. Select a file. Enter email addresses. Click Transfer. Download the emailed file.