how do you make my yahoo my homepage?

Hi, the first step is to load the page you want as your home page. Then use one of the methods in this article to make it so: How to set the home page.

Does it work?

Note that there are two ways (maybe more?) that your choice could be overridden with another page:

• Custom settings file user.js (see: How to fix preferences that won't save)
• Add-ons

Since add-ons is a big topic, let's come back to that if your preferred page doesn't stick.

The Question details show Firefox OS?

Is you question about that platform or about the desktop or other Firefox version?

If this question is regarding Firefox OS then there is no way to change the home screen at this moment.