Do I pay capital gains taxes on the amount of the sale or on the net amount received.
Neither.
You pay capital gains taxes on the amount of capital gains you have from the sale.
Your capital gains is (price_sold) - (cost_basis) - (cost_to_sell)
Since it’s a rental property, you had depreciation.
That depreciation decreased your basis in the property (increasing how much cap gains you will have when selling)
You don’t say how much depreciation you claimed on your taxes (or should have claimed on your taxes) - nor what you originally paid - so we do not know your cost basis.
Costs to sell would include anything/everything to sell - largest would probably be realtor fees. But could be other things as well, such as repairs/improvements done to make it more marketable (ones which you aren’t counting as rental expenses)