The best way to contact Customer Support is through this form.

https://eurail.zendesk.com/hc/en-001/requests/new

Customer Support is currently overloaded with requests so you will probably have to be patient to get help. Please let Customer Support know what date your travel will start so that they can prioritise your request correctly.

Try to describe it here-some of the regulars have by now seen so many of it from 1st time starters that they know a lot of tricks and how to resolve.