No commas. A colon would work.
Student or Learner
- What I want to say is(,) Albert Einstein is truly a genius.
- What I want to say is(,) if you study hard, you will pass that exam easily.
I tried to write two sentences. I would like to ask if I should put a comma in each sentence or not.
No comma. You could add the word "that" instead.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.