I think i have a soft palate canker sore in the back of my throat, it hard to put an ointment on it cause its so far back. how do it treat this?

Aphthous ulcer: Try warm saline gargle for 1 week and it should resolve. Take advil (ibuprofen) or Motrin for the pain as needed.

Mouth rinse: Unfortunately there are no good remedies for canker sores and causes are often unknown. The best treatments are usually just to treat pain, not to cure the sore. My personal favorite is what most call magic mouthwash. It is 1/3 Benadryl (diphenhydramine) (to reduce inflammation), 1/3 viscous Lidocaine (to reduce pain), and 1/3 maalox (to make it stick). You rinse and spit or swallow. Ask your dentist about it.

See a doctor: If it is indeed a canker sore, they typically need to run their course and can only be treated palliatively. There are some anesthetic rinses your doctor can prescribe, and there have been some interesting results using lasers on these lesions. However, you should definitely see a doctor if this does not resolve within 2 weeks of it's initially presentation.