Your website builder has to support dynamic fonts (see link) if you want to specify fancy fonts, and your visitors will have to download them to see them. Basic HTML supports five font families: serif, sans-serif, monospace, cursive, and fantasy. Exactly what fonts are used to display these types depends on the browser.
You can specify other fonts if you’re reasonably sure your visitors will have them on their computers. If you put in your HTML code, it’s just going to display the user’s default for 99.9% of your visitors.
Remember there’s really no such thing as a WYSIWYG html editor. After you put your web pages up, look at them with other people’s browsers. In some cases they will look quite different.