A problem I have with getting a box on my home page for visitors to sign up for a mailing list?
As peterdnz says, the documentation is at https://docs.civicrm.org/user/en/latest/email/set-up/ (Using a Profile). 
For WordPress I think the easiest way to display a form publicly is by using a shortcode. After preparing a WordPress Page, click the CiviCRM button above the editor. For Page Type select Profile. On the next drop-down that appears, select the name of the profile that you have created. Select Edit on the radio button option just below the drop-downs, so that you give users access to edit data in your database (i.e. to add their email address and name to your database). Click Insert Form and the shortcode will be added to the editor.
Hope this helps