trying have colors fade to gray on banner

[lesliecakes]

im very clueless as to how photoshop works. im trying to make a banner with a picture i have im trying to figured out how to invert the image im using which is a white tree with a gray background i want to have the tree black with a light gray or white background and then from the tree i want the background to get darker as it goes if any one can help me figure this out i would be thankful. been sitting here for a good couple of hours and i cant seem to get it . thank you

 

[IamSam]

You need to use the Gradient Tool.

Select the Gradient Tool. Click the Gradient Tool Editor in the tools option menu bar.


Make sure the gradient is set to Foreground to background, by clicking the first Gradient Preset.
Click on the Left Gradient stop (Red arrow), Then click on the Color window (Black arrow) to change the color of the gradient at the stop.


Select the color of choice. Do the same for the Right Gradient stop.

Make sure the gradient is set to linear (Tools option menu bar).

On a new layer (separate from the logo layer) hold down the Shift key and drag the gradient from right to left.
If you don't like it, hit Command + Z to undo an try again.