Hello Sophie :)
First of all I wanted to Welcome you to Wattpad! I hope you come to like this site as much as I do, though, I'm pretty sure you will.
To help you get started on Wattpad I suggest you take a look @Writing-101, there's a guide that helps you update your profile, tells you how to upload stories, create story groups and how to add Book covers. [Feel free to leave any suggestions on how to improve]
If you have any other questions, feel free to let me know, I'd be more than happy to help you out with whatever I can, just like the other Wattpad Volunteers you can find here: @WPNinjas!
The Discovery tab is perfect to find new stories, as is the Wattpad Shuffle (you can find it in the right hand corner of this page). And if you want to talk about random things, need help with your stories, want some story suggestions or just feel like making new friends, then pay a visit to one of the Wattpad Clubs. I'm sure you'll find what you're looking for.
Have fun on Wattpad!
~Vicky