One way is to enter through https://sites.google.com/- in that way you will see any previous sites you have created.
However, a simple way is to go through your Google Drive and select
- Google Sites
Make sure to name your site and then publish it. If you would like to add editors to your site select the icon that looks like a person and a + and choose who you would like to add.
Embedded below is a GIF followed by a 59 second YouTube tutorial.