So I have gotten this far.........But still can't figure out what to do from there. The brush or eraser tools do nothing to the mask. I have never understood how those things work :S
I'm very sorry, I should have asked about your skill and experience with Photoshop. It's hard to tell based on a single post and I made an assumption.
Step 1
Hit Command/Control + J to duplicate the Chest image layer. Turn off the original layer.
Step 2
Highlight the duplicated Chest layer.
Remove the background from Chest image. You will need a darker background in order for the effect to be visible.
I just used the Magic Eraser Tool for this. Tolerance was set to 35. Highlight the layer and click once on the white background.
If you look, you will see that there is some white left over in the handle, you will have to click on these areas as well.
Step 3
Hold down the Command/Control key and click once on the add a new layer icon located at the bottom of the layers panel.
This will add a new layer BELOW the duplicated Chest image layer. If you don't understand this step, just create a new layer and drag it below the duplicated Chest image layer.
Fill this layer with the dark color of choice............I used black.
Step 4
Now add a Color fill adjustment layer. I use this because it's very easy to adjust the color.
Go to LAYER > NEW FILL LAYER > SOLID COLOR
A window will pop up. Name the layer. The Color Picker will pop up, set the color to choice........I used yellowish white.
Note that the layer mask is white. We need to reverse it.
Click on the layer mask to select. It will have white brackets around the layer mask. Hit Command]Control + I to invert the mask.
The mask should be black now.
Step 5
With the layer mask of the Solid Color layer selected, choose your Brush Tool.
Choose a soft round brush set to 0% hardness
Set your foreground color to white.
Paint on the layer mask in the areas where you want the Yellowish White solid color to appear.
You will have to lower the settings of the brush. This will take some experimenting and practice. Change your foreground color to black to paint out mistakes.
Layer mask tutorials
Photoshop:Understanding Layer Masks
Masks: Editable Selection
Layer Masks
How to use layer masks in Phtoshop
Blending photos together: Photoshop layer mask tutorial