You have been working on your farm and now, you are seeing the fruits of your labor. It is very satisfying as every last bit of your farm produce can now be sold to the market. But, as the old saying about counting the chickens before they hatch, you should not list it as a sale since the road is long and you don't know if you will lose some farm produce. It would be a wise practice since you won't be disappointing with the lost farm produce if you manage to lose any of them along the way.
Connect the tractor to the trailer before going on your way. Remember to practice some safety precautions, so there won't be any accidents. The game has a timer and you need to deliver the farm produce before the timer expires. Every level will be different from the other. You will make money based on the number of delivery you made, so keep that in mind. Anyway, should you lose any of the cargoes, just try to deliver the remaining farm produce to the market. You would only need to deliver the required number of farm produce to the market to proceed to the next level. You earn money after every delivery and you can use it to upgrade your trailer.