Joguer is located at: Joguer's Herbs and Roots
To be able to buy the spells you'll need to do a pupil quest for Joguer:
You say, "I want to be your pupil."
Joguer tells you, "I am glad thou art here; I am willing to make a trade. I stumbled across a formula for speeding the growing process of certain plants, but it has fallen into the hands of the scoundrel <NPC>. I will teach thee the small magicks I know if thou wilt but retrieve this formula for me. Do not let her deceive thee, <NPC> wishes nothing more than to selfishly delay my harvest."
Now move to the mentioned NPC.
You say, "I heard you've got a certain formula..."
<NPC> tells you, "I have the formula of which you speak. I am reluctant to give it to you, however, as I believe that Joguer's motives are not as noble as he claims. If you prove to me your strength of purpose by slaying a <CREATURE>, however, I will defer to your judgement. Hurry now, else Joguer's lovely harvest of poison will be delayed!"
You killed <CREATURE>.
Return to the mentioned NPC.
You say, "Hello."
<NPC> tells you, "Very well, here is the formula. I am not happy to be giving you this. I believe that you have disrupted an important course of events. But, that is not your concern really is it. You just want to get your spell and be off. Well, I suggest that you do just that."
You recevied an Alchemical Formula. Now return to Joguer and hand it over to him.
Joguer tells you, "Ah, at last. Thou hast done a great service not only to thyself but also to the entire realm. These plants may change the course of history. They are an antidote to a terrible disease that is beginning to spread through the land. Come to me when thou would learn from me, friend."
If you ask him for bags of firesand, he will sell you some for a very expensive price.