Log into the WeWeb platform and open the editor for the project where you want to create the modal popup. Head over to the "Components" section in WeWeb. Find the "Modal" component and drag it onto the canvas. Make sure its initial visibility is set to hidden. Click on the Modal component to tweak its properties. Adjust the width, height, background color, and other styles to fit your design needs. Drag and drop extra components like text, images, buttons, etc., into the Modal to build the content you want. Customize these components as needed. Add a trigger element on your main page, like a button or link, that users will click to open the modal. For instance, drag a button component to the spot you want on the page. Select the trigger button and go to its action settings. Add a new action, usually a click event, to change the modal's visibility from hidden to visible. To let users close the modal, add a close button inside it. Select the button and set its action to hide the modal when clicked. Preview the project to test the modal. Click the trigger button to make sure the modal shows up as expected and that the close button works. Make any needed tweaks based on your test results. Adjust styles, visibility settings, or actions to finalize the modal popup. Once you're happy with the modal popup, save your changes and publish the project to make the modal live on the website.