Header repeat

you probably can change the header width option in functions.php of your theme; look for a line similar to:
define( 'HEADER_IMAGE_WIDTH', apply_filters( 'twentyten_header_image_width', 940 ) );
(example taken from Twenty Ten)

or simply to stop the repeat, try and add this to style.css:

#masthead { background-repeat: no-repeat!important; }

https://www.w3schools.com/css/css_background.asp

Thankyou its sorted ??