How do I set an ASP.NET Label text from code behind on page load?

I can’t seem to find an answer out there for this. Here’s the scenario:
I have an ASP.NET project using C#. I’m loading data (Username, email, etc…) from a sqlite database with C# (using ADO). I’ll be loading the data into static Global variables in a class file in my App_Data folder. I need to be able to insert the username into an ASP.NET Label on a page during load.