Relevant articles:
Projects: https://help.symplify.com/hc/en-us/articles/360011049480-Projects
Skins: https://help.symplify.com/hc/en-us/articles/360011224780-Design-your-Skins
Snippets: https://help.symplify.com/hc/en-us/articles/360011050920-Snippets
Email content builder: https://help.symplify.com/hc/en-us/articles/360011213699-Edit-email-content