Knowing HTML and CSS won't help you much when it comes to myspace. Espicially if you're trying to make a layout. The layouts made with editors have no HTML in them it's purely CSS that styles the 'default' HTML that is already there placed by myspace. Furthermore, they use a table layout wich makes things 10 times worse. To top it all off they use extremely specific CSS, down to the table divisions, and spans.
Also you never know if what you enter will work sense myspace can edit the HTML and CSS you enter. It takes time and effort to be able to program a myspace page, this is something most people don't want to deal with.
Nothing in what i've told you so far will be of any use unless you actually know HTML and CSS. You said that you're learning it. I hope you're learning through an up to date book. A lot of people will recomend
w3schools, but this isn't really a good place to learn it's more of a reference and it leaves out some important details that you will need if you ever want to become a good web developer.
Hope it helps, Thanks, Death