No expert here, but in Photoshop (and I assume Fw would be similar) I would—
double click the layer in the layers palette and rename it from Background to anything else
select the magic wand tool, set a very low tolerance in the toolbar top left, click in the white area to select all white pixels, and press delete. That changes the white area to transparent.
choose the black decorations with the same tool to select them all and then change their color
create a layer below the decorations and apply a gradient to that.
A couple of far easier and non destructive method , since you are fortunate enough to have a grayscale pattern.
Create a NEW shape layer that covers the whole canvas.
In that layer go to Fx and make a gradient overlay to match the gradient in your desired image ( which seems like a basic linear gradient , so that should be a snap).
If it wasn’t already, move the shape layer BELLOW the pattern layer
Set the pattern layer blending mode to multiply.
You can even have COLOR versions of your patterns by employing this method.
Copy your pattern into the clipboard.
Create a shape layer, covering the whole canvas, of the desired color.
Add a gradient mask to the shape layer
Option click ONCE on the gradient map ( the canvas should turn white) , and PASTE your pattern ; it is now pasted onto the layer mask you just made
Select ALL then , INVERT ( so that black turns to white and white to black)
Create a new shape layer
In that layer go to Fx and make a gradient overlay to match the gradient in your desired image.