Talents add +1D to tests with a certain skill specialization. Talents apply to a specialization, not a skill; you don't have a Talent with Space Transports, you have a Talent in Space Transports: YT-1300 or Space Transports: All-Out or Space Transports: Dodge; the last two aren't usual specializations, but they work for talents.
Humans begin with 2 free talents; anyone (including humans) may spend 1D of skill dice to begin with 2 (additional) Talents. In play, Talents cost 5 CPs per talent. Talents do not require a teacher; they are a natural ability (that may have been latent until now). If a player has 5 CPs, they may acquire a Talent at any time, with the Game master's permission. Talents are a bonus; they do not increase the cost to improve a specialization, as they do not increase the rating of the specialization.
You may have only one talent per skill, but you do not need any training in the skill to make use of a talent. You may have no more talents in a single attribute's skills than dice in that attribute (so, if you have 2D+2 Dexterity, you can have 2 Dexterity skill Talents; if you increase it to 3D, you can learn another Talent.)
Force Powers and Advanced Skills: Beginning characters may not have Talents in Force Powers (other other Metaphysical skills, depending on your system) or advanced skills; these must be acquired in game. You may have only a single talent per Advanced skill. You may not have talents in the Force Skills, themselves. A talent with a force power applies +1D to the use of the power; you may have no more talents in powers associated with a single Force Skill than dice in the Force Skill. Talents with Force Powers that rely on multiple skills (q.v. Lightsaber Combat) require only 5 CPs, like other Talents, but count against the limit of both Force Skills.