• The unit pictured in the toolbar is selected and ready for work. It will also appear on the map with a flashing white outline (currently hidden by this window).
• The Engineer builds roads from where he is into the adjacent tile.
• The Engineer takes 1 turn to build road through most tiles, except hills, mountains and swamps, which take longer. 
• It’s a good idea to continue using the Builder to develop more Grain Farms and other natural resources.
• Click the question mark button on the lower right of the Main Map screen to bring up the Help briefing for this episode. It contains further explanations of the very important concepts of road networks and knowing which tiles are connected. 
• For more help, click on the question mark button. The Help briefing for this episode also discusses the unit cycling buttons in the toolbar.