Deprecated codex?

Notice: add_custom_image_header is deprecated since version 3.4! Use add_theme_support( ‘custom-header’, $args ) instead. in D:\hosting\8741014\html\wp-includes\functions.php on line 2628

Notice: add_custom_background is deprecated since version 3.4! Use add_theme_support( ‘custom-background’, $args ) instead. in D:\hosting\8741014\html\wp-includes\functions.php on line 2628

Notice: has_cap was called with an argument that is deprecated since version 2.0! Usage of user levels by plugins and themes is deprecated. Use roles and capabilities instead. in D:\hosting\8741014\html\wp-includes\functions.php on line 2712

These errors are appearing at the top of my dashboard and on the actual site. How do remove them or fix the errors?
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