how do I use the getwalletinfo RPC?
getwalletinfo does not take parameters.

It sounds like what you are looking for is how to send getwalletinfo to a certain wallet loaded into Bitcoin Core. The way to do this is to use that wallet's API endpoint. The endpoint is /wallet/&lt;name&gt; where &lt;name&gt; is the name of the wallet you are trying to send commands to.

So the full URL that you need to send your RPC requests to is http://&lt;ip&gt;:&lt;port&gt;/wallet/&lt;name&gt; where &lt;ip&gt; is the IP address that Bitcoin Core is listening on (probably 127.0.0.1), &lt;port&gt; is the port the RPC interface is bound to (probably 8333), and &lt;name&gt; is the name of the wallet.