The crypto trader can only work with USD in your Bitstamp account. If you have Euros in your bitstamp account, you must first convert them to USD. This is simple and works like this:
1 – Login to bitstamp.net
2- Select market EUR / USD at the top left of the screen
Then click on Tradeview in the menu at the top right
Now choose sell – Instant and enter the amount of Euros you want to sell
Then click on sell. At the top of the screen (black bar) you immediately see that the available how many euros have decreased and USD has increased.