You poor, poor fool…
First, take the Patron talent. This gives you the ability to learn magic and petty enchantments. It also gives you one free Master of Formulae talent.
The Patron talent does not have any upfront cost (apart from the usual XP cost for a talent) but does add Upkeep.
You can only ever have one Patron at a time.
Losing your patron is bad. Very bad. Core book p.169.
Second, take the Sorcery talent. This teaches you one spell, at a cost of (5Ψ + the spell's To Learn cost) permanent reduction in Resolve.
To learn additional spells, take either the Pact talent or the Barter Your Soul talent. Both of these can be taken multiple times.
The Pact talent is when a mentor teaches you one spell, at a cost of (the spell's To Learn cost) permanent reduction in Resolve. Like the Patron talent, this adds Upkeep.
Each mentor can only teach you two spells (you can only take the Pact talent once with your Patron because they have already taught you one spell).
The Barter Your Soul talent is where you teach yourself one spell, at a cost of ((X+2)Ψ + the spell's To Learn cost) permanent reduction in Resolve, where X is the total number of spells you know including this new one. Learning a spell this way does not add any Upkeep since there is no mentor involved.
Harsh, isn't it. I hope you have a lot of Resolve. You should also consider the Discipline talents.
Your teachers require payment. During Downtime, when paying Upkeep, roll 5 combat dice for each rank in the Patron and Pact talents you have. This total must be paid using a combination of gold, Vigor, and Resolve.
The Patron (i.e. the GM) chooses how the payment must be allocated between gold and Vigor and Resolve. Evil grin.
Stress will be recovered afterward, but any Harms taken must be healed as normal.
Samix the Sorcerer has a Patron of Gribblemonster, a creature from the Outer Dark, who has taught him two spells. He has also learnt two spells from the Black Ring organisation and one spell from a powerful sorcerous item he stole (this item requires regular payment in blood).
His talents look like the following:
Patron (Gribblemonster)
Sorcery
Pact (Gribblemonster)
Pact (The Black Ring)
Pact (The Black Ring)
Pact (sorcerous item)
He knows six spells (an extremely impressive number) and pays 30Ψ Upkeep (!) for this, which must be split between gold, Vigor and Resolve. With that many spells, he probably doesn't have much Resolve, so Upkeep will be either expensive or painful or both. Probably both because the item won't accept gold…