Kinesis ranges from hard to impossible ..however , pyrokinesis ranges on the more harder scale..however , it is useless.
With pyrokinesis , you do not and should not expect it to be exceptionally fancy or great like throwing a actual fireball etc. Those are fluffy and stupid.
What you could do is make energetic constructs with fire , push your energy into the flame to make it larger and take away energy from the flame to make it smaller. And also affect temperature via the use of fire's energy..it dosen't seem and is not something you would want to learn..as the skill is rather useless.
I can suggest you several research materials and books if you insist on going through this useless study , but know this well..you do not create fireballs , spontaneously create fire and all those fluffy nonsense.
Real pyrokinesis is rather useless and a stupid study..so much so that many practicioners call it fluffy..and i myself label all kinesis to be fluff too , whether it is possible on any minute degree or not..