There's not much to it. Wikipedia sums it up well:
Keep in mind that in the context of graphic design, it's somewhat of an arbitrary building block. As such, it seems to be abused much more than used meaningfully.
Barring nothing else to go off of, staring with the golden ration isn't a bad thing. Just don't let it cloud other more tangible objectives.
In terms of web design, it's even less practical than the fixed canvas you get with architecture or print design.
The catch is that in web design, you less often have control over limiting vertical divisions. While you can provide a hard-stop for widths, you usually need to accomodate flexibility in vertical content/layout flows. As such, the golden ratio tends to fall a part a bit.
I'd suggest that if you have absolutely nothing to start from, while the golden ratio could work, for web design, there's probably better foundations to consider such as the many CSS grid systems out there.