Hello everyone! Well, as you probably noticed, I'm a new girl in subeta. I know some things about encoding and HTML, but I do not know anything about the profile layout and etc... Could you help me, please? :)

Go to your profile and add sections - profile. Then you can change the background of your profile or make it blank and add CSS.

Sorry, I didn't get it :( I am in my profile. Now I click "edit my profile", then add content... Is it right?

Yes.

I also have been having problems with adding a layout,but no success to far.And this really didn't help me.

There are a bunch of resources in the sticky Useful Profiles and Graphics Threads thread. That's probably the best place to start if you want to style your profile.