You don't pay anything. Exploriada adds its commission to your own prices. Then, the end-user price for any product is your price plus Exploriada's commission. Any reference to net price means partner price without a commission added. Your net price should include all taxes you owe by law in your country.
You do not need to do anything to calculate the commission. It is automatically added to the product's price in your Tour Management Centre.
For example, if your price is $80 and the Exploriada's commission is 15% per product, the user pays $80 + $12 upon booking ($92 in total). Exploriada keeps $12, and your value ($80) is transferred to you.
You can check what Exploriada's commission is on your products by going to the Payments screen.