When you've draggeed the pieces into place so that the train can drive from left to right without getting damaged, you can hit the play button to start the train. The arrow keys can help maintain some balance to your building blocks, and it matters where exactly you're holding the shape in order to turn it just the right amount. Use the mouse or long-press with your finger to grab a block and move it wherever you want by dragging it across the screen. These pieces are the necessary pieces that form the train track, and only you can help the train arrive its destination.
Mini Train is a puzzle game where you drag blocks and shapes that are scattered around the platform in order to make way for the oncoming train.