To use Framer for web design prototyping, you need to sign up for a free account and create a new project. You can choose from different templates, or start from scratch. Framer has a split-screen interface, where you can design your prototype on the left side, and code it on the right side. You can use the drag-and-drop editor to add elements, such as text, images, buttons, icons, and shapes, to your prototype. You can also customize their properties, such as color, size, position, alignment, and opacity. On the right side, you can use Framer's code editor to add logic, functionality, and interactivity to your prototype. You can use Framer's own language, which is based on JavaScript, or switch to HTML, CSS, or React. Framer also has a library of pre-made components and snippets that you can use to speed up your prototyping process.