With Stastic, you can create a new website (see the section “[How to install Stastic?]”). Stastic will ask you for a name and will create a “repository” on Github (this is how Github calls your “projects”).
You can access the created files at all times in your github account, see Github documentation here or simply head to github.com, login an look for “Your repositories”.
In order to access your live website, if you have lost the address, you need to go to the repository as explained above, and then open the repository settings. There you will find a section called “Github pages” with the URL of your website. Click on it and you will be brought there.
Next you probably want to know how to access your website’s admin (Stastic editor), then take a look at the section “How to access Stastic admin?”.