How to edit the domain I've got through namecheap.com connected to my GitHub account?

I've got a one year free web-domain from the namecheap.com through GitHub education program and now I want to edit the domain and by edit I mean I want to make it a blogging site, I've tried Google and couldn't find any help, so now I just wanna know how do I start editing the domain? There's repository created in my profile but I just don't know how to start.