Wrong forum topic, but I'll try to answer, anyway lol:
Similar to profile editing, you edit blogs using CSS and the <style> tags (and make sure to hit the <> button so your CSS code actually works lmao). While I haven't actually edited nor made a blog, I've edited bulletins before so I'm gonna assume the process is similar :o
There's some classes you edit in your profile that are the same in blogs, such as the SpaceHey logo or the navigation bar (AKA these sections will always use the same code, whether that's in your profile or creating a blog). However, there's some different classes as well. Unfortunately, I don't know the specific sections a blog has. But that's why I'd suggest looking at blog layouts that have already been made! If you look through a layout's code, you can see what does what to a blog. Heck, you should probably copy the layout code and mess around with it :p
If you know the basics of coding your profile, coding a blog shouldn't be all that hard, I think.