Benefiting the writing course, I’d be able to present my ideas on the paper.
How about: Having benefitted from the writing course I’m now able to express my ideas on the paper. I assume you are referring to a specific document such as a test paper?
Isn’t the suggestion here that the writing course has enabled him to express himself ‘on paper’ rather than in speech? This to me sounds more acceptable than that ‘paper’ refers to anything in particular.
Perhaps also - ‘benefitting from the course … I’ll be able …’
In any case the verb benefit needs to take the preposition from as it is usually intransitive. Otherwise the meaning may change as if I am benefitting the writing course (transitively used), which fails to make good sense.