WordPress now works in content blocks. To add content (image, text, video, etc.) you first need to add the appropriate block. The most commonly used block will be the Paragraph block (to use when adding text).
You will most often be using the paragraph block and the image block, but there are many more to choose from depending on what you want to do. For example, there is a YouTube block and a Google Maps block. Just add the link to the YouTube video or a link/address to a Google Maps block and they do the rest for you.
Here is a link to the WordPress documentation that addresses how to use every little bit of the block editor.