First ensure WASM is fully loaded. The buttons should become enabled, and a massage with some WASM status gets added to the bottom.
You can click the "add" button to run a simple test, making sure that WASM works. "Ping" sends a message all the way to the web worker, and should give the RTT in milliseconds.
Then you can start the rustradio graph and upload a 32bit complex float I/Q via the browse button. It'll use 50ksps by default. Rustradio will run on it, and will give you the bytes for the first 1200bps AX.25 packet decoded.
The code is on github, though I plan to integrate it as an example in the RustRadio project.