You can change the header in VIP cart, please do following steps.

If you are using Blue theme then,
Create your header image and save it in four different sizes and name as follows.
1. 571x193.....header1.jpg

2. 308x194.....header2.jpg

3. 331x194.....header3.jpg

4. 900x 193....header_bg.jpg

Upload all these four images on following location.
templatesblueimagesheader1.jpg
templatesblueimagesheader2.jpg
templatesblueimagesheader3.jpg
templatesblueimagesheader_bg.jpg
=========================================

If you are using maroon theme then, you need create the header image in two differnt sizes and name.

header.jpg..........960x274
header_pic.jpg... 348x274

Upload both images on following location.
templatesmaroonimagesheader.jpg 960x274
templatesmaroonimagesheader_pic.jpg 348x274

You can check the changes by refresh your page.