Welcome to Roll20 Stephan, I'd start by checking out this thread ... it's full of useful tips and tricks to get started (please note that we are aware of the issues with the tutorial at present... don't judge us on that, it's still a useful intro to the VTT!). Once you have worked through that you can create your own game to act as a playground of sorts, ensure to add a 5e sheet (both the OGL and Shaped sheets are popular) and you can create characters to your hearts content. To use them in other games you'll need either a subscription or 5 minutes to manually transfer the data into a game you have been accepted into :) The community here is awesome but please be aware that we like to keep the forums Roll20 specific so as long as you have questions that pertain to the VTT (like this one you've asked) you'll be golden!
