Open your Firefox browser. In the upper right corner there are 3 dots, click there. Then find the Settings menu tab, then Locate the Home tab. In the Home tab it gives the option to set your Home page to be wherever you would like. That can be Mozilla Home page, your favorite website, or Firefox Home. That should be all you need.

Edition to the above comment.... In the Home tab settings, you are given an option to chose your default sites to show first. Also your Home settings are located under General.

I've done that already. My homepage is set to www.msn.com, but how do I get Firefox to go directly to my homepage when I start Firefox?