When you first upload the theme to your blog, it wont look 100% like the demo for several reasons.
01 New Blog
If your blog is new, you might have to remove some old widgets that Blogger automatically adds. They usually go to the first available section, so that would be either the Menu section or the Header section.
Just go to Theme and remove the unnecessary widgets. The only widget in the Menu section should be the Pages widget and the only widget in the Header section should be the Header widget; everything else can be removed.
And your blog will be empty, which is another reason it wont look immediately like the demo.
02 Old Blog
If your blog is not new, then you might have to remove the widgets that are left over from your previous theme. Again, this can be easily done from Theme. In case any of the widgets are locked*, this is how you can unlock them to remove them:
- Go to Theme > Edit HTML > click on "Jump to Widget" (the first button from left to right from the right side of the page.
- Select the widget you want to remove from the list.
- Change true to false in locked='true'.
- Save the changes and go to Layout again; you might have to refresh the page, but now you'll be able to remove the widget.
*Locked Widgets: If a widget is locked, you will not be able to see the "Remove" button when you open it.