Hi SarahLorne and welcome to the community!
The $50 usually takes up to a couple of working days to process so it can take a couple more over a weekend. Make sure you check your email inbox and spam folders as from time to time new members are asked for ID checks before being credited their starting capital. If you haven't heard after 96 hours or so, I'd start with writing a ticket to the support crew
here.
In the meantime you can familiarise yourself with the Basic strategy articles (under the "Strategy" tab above).
If you have any other questions don't hesitiate to ask.
Have fun and good luck.