Hello sorry I heard that Binance has no fee, so there is no fee to pay opening a position?
Let's say I wanna trade BTC/USD or BTC/Ripple... I exange them (buy or sell)... well do I have to pay any fee for this on Binance or not?
Binance does have a fee and as Yuuto said it is 0.1% as listed on their website. They had no fees for a while but changed their fee structure last month(check here for their announcement: https://binance.zendesk.com/hc/en-us/articles/115001258291-Binance-Will-Charge-Trading-Fees-From-August-25)
So yes, if you were buying XRP using bitcoin on binance then expect to pay a trading fee, although not a big one at all.
Though since binance is located/based in china, i would not use them for large exchanges but rather go to bittrex because of the ongoing speculation on government regulation.