QR Codes can encode any text. However, it is best if they are URLs that lead to webpages. The QR images will be smaller with larger and fewer pixels, so they are more easily captured from photos and with cameras from a distance.
If you have access to change the website, try to select generic URLs so that the same QR code can be used for future instances. That way, you will not need to update the QR; you’ll only need to update the web page it points to. For example, https://resources.indivisiblepv.info/tag/upcoming-event/ or https://indivisiblepv.com/events-1.
The real work is creating web pages with good copy and design.
To generate a QR Code, use the latest Firefox with the “QR Code” Extension (by pudymody). After adding the extension, the end of the URL field will have a square icon that looks like a small QR code. Go to the page that you want for the QR, then click on the icon. You’ll be asked to save it as SVG or PNG. SVG is recommended because it can be scaled up to large sizes with crisp edges.
Next, scale the QRs to the desired size when printing the QR file with the browser pointing to it, or with a graphic program. Cut out and stick to signs with clear packing tape. Or include the QR image in other web pages.
See also: For Editors on how events are managed.