A dashboard shows several sheets on one screen. Click New Dashboard next to the sheet tabs. The Dashboard pane on the left lists your sheets: drag one onto the canvas, then drag the next one onto an edge of the first. A gray area shows where it will land: drop on the right edge to put the sheets side by side, on the bottom edge to stack them.
Each sheet sits in a tiled zone with its title on top. The title is the sheet's name, so name your tabs before you build the dashboard: double-click a tab to rename it.
Size matters more than it looks. New dashboards use a fixed size (Desktop Browser, 1000 x 800): the layout looks the same on every screen, but small screens get scroll bars and big ones get empty space. Automatic fills whatever window opens it, and the charts squeeze or stretch to fit.
The Objects list adds Text, Blank space and containers.