Region types

Open the Insert tab. That is the catalogue for everything except charts, which have their own Plots tab.

Two entries are not placed as blank blocks at all. A slider is attached to a math assignment from the context menu. A section table is built from the headings you have already marked.

Every type you can place

Type	Where the button is	What you get
Math	Insert, Insert Region	Expressions, assignments, and answers. This is also what typing on empty paper gives you.
Text	Insert, or double-click empty paper	Notes, headings, and lists. Mark a text region as a numbered section on the Text tab.
List	Insert, Insert Region	A dropdown. Each entry injects its own variables into scope when you choose it.
Sweep	Insert, Insert Region	A parametric table: vary one input down the rows and tabulate expressions across the columns.
Summary	Insert, Insert Region	Labels beside live-linked answer cells.
Line	Insert, Insert Region	A horizontal rule — a text region that is only a separator. It spans nearly the full page width and ignores where you clicked horizontally.
Picture	Insert, Insert Region	An image from a file. Pasting or dropping an image on the canvas does the same thing.
2D Frame	Insert, Insert Region	Sketch members, supports, and loads, then solve.
3D Frame	Insert, Insert Region	The same sketch, in space: orbit, pan, and place nodes on XY, XZ, or YZ.
Line, Area, Scatter, Bar	Plots, XY Charts and Bar chart	2D charts drawn with Chart.js. Bar draws one horizontal bar per entry of a dropdown list.
Polar Line, Area, Scatter	Plots, Polar plots	The same three series types plotted as theta and radius.
3D Surface	Plots, 3D	A surface z = f(x, y) over a grid of two inputs.
Section table	Text, Sections group, Table	A clickable contents list built from your section headers.
Slider	Right-click a := assignment, Add slider…	A drag handle bound to that assignment, not a region you place yourself.
Input box	Right-click a simple name := number assignment, Convert to input box. Select several to convert and align them together.	The number becomes a field. Convert to math restores the formula. Pair with Lock format so only those fields can change.

Later sections cover how to fill each type in. What matters here is recognising the button. All of these are regions. Whatever you insert, you can select it, move it, resize it, and copy it with the same gestures.