Cyanine is the modern, lightweight and flexible standard theme for Typemill. You can activate a landingpage, setup different content sections for the landingpage and order them like you want. You can also change the colors, fonts and other details. To configure the theme, login to the system (/tm/login), go to the theme settings (/tm/themes) and choose the theme "Cyanine".
If Cyanine does not fit to your needs, then you can also choose another theme in the theme store of Typemill.