Ships and caravans are ``drafted'' as if they were armies, and should appear in your [l]ist of available armies in the [a]rmy menu. The construction and maintainance costs of ships and caravans are tabulated with those of other army types. Note that some spirits also behave as ships and caravas, in that they have the [c]argo flag. Examples of this are the flying carpet, the ghost ship and the living ship.
A single cargo hold can only transport a certain amount of goods. The unit of weight is the weight of a single person, and a caravan can transport 250 person weights. A bar of metal weighs 0.1, money weighs 0.01 for a sheckel, food 0.05, a jewel basket 0.01. If you load soldiers, their weight is equal to the weight of the number of people plus the weight of the metal used in drafting an army that size. Any caravan can transport only a single army and a single land title. The land title does not have significant weight.
To load a caravan or navy, you select it (with [a]rmy commands) and then use the [t]ransportation command to [l]oad goods, which can be [s]hekels (money units), [m]etal, [f]ood, [p]eople, [a]army or [t]itle. To unload it you move the caravan or navy to its destination and do the same with [u]nload instead of [l]oad.
You can only load certain goods onto a caravan in certain places. Anything can be loaded in a city. Metal can also be loaded in metal mines, jewels in jewel mines and food in farms. The title to a sector must be loaded on that sector itself. People can be loaded from any of your own populated sectors. Armies can be loaded anywhere in your land, but out of your territory they can only be loaded if they have the front-line flag.
To unload in a foreign land you must be in a trading post, or you can unload armies with the front-line flag (for example, Sailors, Marines, Scuba divers). To trade an army in a foreign trading post, you should put the army in TRADED status, and then unload it on the trading post. Alternatively, since armies move on their own, you can put them on TRADED status and just walk them up to the trading post. When you stop that army on the foreign trading post, you will be asked if you really want to trade it. You can also change the army to TRADED status once it is already on the trading post. In all cases you will be asked for confirmation of the army trading.
Transporting goods within your country is kind of useless. In your land, goods must be unloaded in trading posts or cities. Transporting people is an effective way of getting them to the better mines and farms. Transporting armies can help mobilize your forces more quickly, since you can then unload them and they can still march.
Some armies, such as Sailors and Marines, have ``front line'' flag (see the army types table). This means that they can be unloaded from caravans and ships anywhere: in your land, in un-owned land, and in foreign land. Thus ships and caravans can be used for transportation of fighting troops, not just for trade and migration.