The quest “Increase Your Cargo Capacity” asks you to send 2 complete shipments. After you finish it, you will have 7 crates in your railcar. A complete shipment is when you fill the first 2 crates with what they indicate and the rest of the crates up to their maximum of 100.
The quest “Incomplete Shipments Are OK!” asks you to add less than 100 of a produce in 3 crates, then send the train with an incomplete shipment. The quest is meant to show players that you still get the coins for what you sell, even if you send the train with only 30 corn inside, for example. No need to worry about complete shipments all the time 🙂
The quest “Earning the First Train Ticket” asks you to install the liquid level gauge on the railcar and fill it to earn 1 Train Ticket.
The quest “Recipes to Town” asks you to send 20 complete shipments so you can order a cooler and ship recipes to the town. You have to do the first part of the quest (the 20 complete shipments) before you add 1 railcar, then select the cooler for the second railcar. Again, a complete shipment is considered when you fill the first 2 crates with what they indicate in the specified quantity + the rest of the crates to 100.