Those of you that use tumblr?

[♥ ιм ℓιтєяαℓℓу fαℓℓιиg fσя уσυ ♥]

I just made one yesterday and I'm really confused on how it works.
What's the difference between typing something under "info" (after you hit customize) and typing something under "text" from your dashboard?
How do you put tabs under your picture?
Like this one for example.. how they have "Haters you can go kill yourself" and "Twitter" and stuff.
How do you know who's following you?
How do you get your picture on the left instead of the right?

I'm so confused. Lol.
Can you help me out/tell me the basics?