Problems importing xml file

all I want to do is import a xml file from my old blog to my new blog.

and this is what I’m getting.
“Unable to create directory /home/lakopha6/public_html/wp-content/uploads/2008/06. Is its parent directory writable by the server?”

I know it has something to do with file permission “thing” but I don’t know how to change it. When I go to the index.php and change the permission numbers, I just get lock out of wordpress.

I also can’t design my blog.I’m getting this…
“You need to make this file writable before you can save your changes. See the Codex for more information.”