Most of this is for somebody who writes code.

The Customize studio changes the colors, images and wording on every screen people see, against a live preview and with nothing to install. Start there.

go.tito.io/acme/admin/looks

Three layers, and you can stop at whichever is enough

A background color. One value in Customize, and every public page takes its colors from it.
Colors and fonts. A whole palette at once, including colors, fonts, corner radius, shadow and motifs, as a theme manifest. That's a small text file of settings with no code in it. Ask whoever does your design, or ask us for a starting point.
Your own templates. The actual HTML your pages are built from, written in Figh. This is web-development work. You can write them one file at a time here, or work on them as ordinary files on your own machine.

Editing a view or the layout here shows a live preview beside it, drawn from one of your account's own events, orders or tickets so it renders with real data rather than a blank page. It redraws as you type, and a compile or render error appears where the preview would be, in the same words a save would show. Assets don't get a preview.

A custom theme is the second and third of those, with a name on it. That name is what every event uses to say what it's based on.

Using your own font

The theme manifest offers a set of fonts we host. If you have a license for a typeface of your own, and somewhere to host the files, your theme can name that instead. Whoever writes your theme file adds the family name and a link to one file per weight. To set it up in Customize instead, see Use your own font.

Three things that follow

Editing a theme changes every event on it.
One theme can be your account default. It's used for your home page, your custom pages, and every event that hasn't picked a theme of its own. Open the theme you want and press Make this the account default, which is also how you change it later.
A single event picks from its own Customize. Open the event, and the Based on block at the foot of the Look tab lists your themes. Choosing one asks whether you mean that event or every event on the same footing.

An event you've put on Tito's default look keeps Tito's own design, and your account theme doesn't reach it.

When your theme's files make up the event page, Customize doesn't offer Tito's starting themes or Layout. Your files decide how the page is laid out.

When a theme was sent up with titogo push, the top of the Look tab in Customize names it, with the name of whoever built it (or their email address, if they haven't set a name) and the day they sent it. To change its design, update the theme where it was built, or put the event on another theme. You can still edit the wording in Customize.