I found a lot of example that allow disabling of form elements on checkbox click, but I actually can have a page loaded with a checkbox selected.

I suppose I need some function that will check if the checkbox (let's call it chBox) checked onload and if yes -- disable the fields. If not leave them active. Also I'll need to add onchange statement to my checkbox to enable/disable form elements.

JS is a bit confusing since i'm more familiar with server-side coding...