Add a generator to the diagram by clicking its button in the toolbar, then clicking where you want to place it in the diagram.

Remove a generator using the "delete generator" button.

Connect ports by clicking a dangling wire or boundary port, then clicking where you want to connect. Valid connection points will be highlighted in red. Connect to boundaries by clicking on the left- and right-hand-sides of the grid.

Watch out: a gap in the boundary will be interpreted as an unconnected port.

Disconnect a wire from a port using the "disconnect wires" button.

Add a generator using the "+" button in the "signature" section.

Add a rewrite rule using the "+" button in the "rewrite rules" section.

Watch out: a gap in the boundary will be interpreted as an unconnected port.

Draw your starting term

Hover over rewrite rules to highlight the part of the diagram that will be rewritten, then click to apply the rule.

The identity wire can be drawn by clicking the left boundary port, then the right.

Drawing the "twist" morphism is similar: click the first left boundary port, then the second right boundary port, and vice-versa.