have you looked at the documentation samples:
https://api4.windy.com/examples/hello-world/

once you have a reference to map, you can use it as documented in leaflet documentation.

store.set('isolines', 'pressure');

hi @ivo - any thoughts about this? forcing a refresh of the model data and the view without having to reload the whole page? this appear to be an issue in https://www.windy.com/ as well - no auto update.

I have not looked myself, but have you gone digging through the code for the isoline plugin:
https://api4.windy.com/assets/v/16.1.0-cc030470/plugins/isolines.js

You might find there are parameters you might manage to configure; or you might be able to make your own custom variant to use in place of this ootb plugin.

Hi @ivo - any news on this? forcing desktop mode only?

What is the URL for this page you have created?

Have you strted by simply copying/pastign the "hello world" example (https://api4.windy.com/examples/hello-world/)?

The Windy API is not really made for that use case. It's really built as a visualization layer that you can customize. Not a standalone headless REST API.

@saaneuvos said in Guide for dummies: How to load API 4?:

testAPI4.php

ah, so the address is https://www.sääneuvos.fi/test/testAPI4.php.

when i try load that page, i see the js console is reporting the following error:
Windy API used on unauthorized domain

Have you authorized your domain (www.sääneuvos.fi) in your API config (https://api4.windy.com/api-key/)? If you have, ivo's code might be having issues with the special characters in your domain name (ä)...

see:
https://community.windy.com/topic/6514/weather-picker-not-working-in-mobile-browsers/6

start with the samples/tutorials at https://api4.windy.com/. just copy the sample html as is into your own html file, put it on your web server, and look at the resulting page. make changes as needed. the samples cover a lot of ground in terms of typical changes folks might be interested in.