Sure, I can help you with that! Here's how you can change the gradient color in a chart for Excel 2007:

1. Select the chart that you want to modify.
2. Go to the "Format Chart Area" option by right-clicking on the chart or by clicking on the "Chart Tools" tab in the ribbon and then clicking on "Format Chart Area".
3. In the "Format Chart Area" dialog box, click on the "Fill" option.
4. Under "Fill," select "Gradient fill."
5. Click on the "Gradient stops" option to see the current gradient stops.
6. To add a new gradient stop, click on the "Add" button.
7. To remove a gradient stop, select it and click on the "Remove" button.
8. To change the color of a gradient stop, select it and then click on the "Color" dropdown menu to choose a new color.
9. To adjust the position of a gradient stop, select it and then drag it to a new position on the gradient bar.
10. To change the direction of the gradient, select the "Direction" dropdown menu and choose a new direction.
11. Once you have made all of your changes, click "OK" to apply the new gradient fill to your chart.