To try writing some WebAssembly, we'll use the WebAssembly Studio tool: https://webassembly.studio/.
This is an online tool that allows you to write code in various languages and have them compiled into WASM. In the WebAssembly Studio web application, if you create a new C Hello World application, you can very quickly get to see some WASM code by building the project:
As you can see, WASM isn't exactly intuitive. However, you can write (or produce this) yourself and have the web browser run it.
This tool certainly gives an inkling of what may be possible with this technology; however, if you're not too familiar with C or Rust, you may struggle to use this beyond displaying 42 in the browser.
Fortunately, Microsoft is working on an experimental technology called Blazor that abstracts a lot of this work behind a familiar-looking project structure...