@markush
The platforms I'm using to trade are bitcoin-denominated. We just use Bitcoin rather than say USD 0R EUR etc...
I trade specifically one pair only @this time of my Forex career. I trade the usd/jpy pair. I started out trading only the EUR/USD but that pair was way too volatile for me@the time!
Pairs are easy to understand once you get a grip on it - https://www.fxcm.com/
https://admiralmarkets.com/education/articles/forex-basics/understanding-the-major-currency-pairs-in-forex-trading