I made Summon Baliwog spell and added it to my custom made npc spell list, but when i went to buy this spell it wasn't there. There wasn't nothing to buy. What i have to do?

You need to make sure that this spell is defined as a spell and not an ability, lesser power, or power. The NPC needs to have the appropriate boxes checked on his services (AI) tab, and needs to have a service package running for the shop to work. The NPC also needs to have enough skill to use the spell themselves, so if the spell is an apprentice level spell, the NPC needs 25 skill with that school, 50 for journeyman, and so on.

Now its on merchants spell list, but when i cast it, Summon won't help me when i'm on the battle.