Are promissory note installments considered capital gains? I'm selling my website and would love insight on the financial details.

Hi, I'm selling a website that I've been running for 3 years and have put significant time/energy/money into it. I understand this would be considered a long-term capital gain when it sells. I'm looking to structure the sale at 1/2 cash & 1/2 promissory note at 0% interest for 1 year. How are monthly note installments considered relative to capital gain tax laws? Would these installment payments be treated the same as the down payment that's made in cash or be considered 'ordinary income'? Is there a certain way to structure the language in the note to allow for the least amount of tax responsibility? Thank…