Build a bridge so that your workers can take objects from the other side of the valley. Select first the terrain where you'll place the bridge. You can play in one of 2 modes: in the design mode you can add elements to build the bridge, but each part has a cost and your budget is limited, so you have to select them well. There's 2 types of bridge elements available: walks and connectors. The connectors are softer and cheap, but your workers cannot stand over them: you need to combine them with walks to build a good bridge. When your bridge design is ready, you can go to the test mode. There you will see if it works or if it has a problem: it can be too weak for the workers' weight, or not to be stable, or slopes so steep that the workers cannot climb them. Whatever, you can always go back to design mode to fix it, and when you finally have a good bridge you go to the next level.
If you move the mouse to the right or left border of the game you'll scroll the scene to see it complete. To design a bridge, start by clicking on the design icon (the one that appears on the upper corner of the game). Select what time of element you will apply (walker or connector) by doing click in the corresponding icon on the top menu. Then drag and drop to indicate at what point will end the bridge (there is a limit on the acceptable length for each section, that depends on the money you have). To delete a bridge section, click on it and then click on the eliminate section icon at the top left menu. Also at this menu there is an icon to restart the level and other to test the bridge (the clock shaped icon).