Developing a piece means moving it from its starting square to a more active one. In the opening, your Knights and Bishops are your most important tools.
The Golden Path: Generally, you should develop Knights before Bishops. Knights are most effective when they jump toward the center (f3 and c3), while Bishops need open diagonals to breathe.
Developing your minor pieces clears the back rank for your Rooks and Queen. Reach a state where your entire army is "mobilized," ready to contribute to your plan.
Task 1: Develop your Knights and Bishops! Select a white piece, then click a target square.