Note: If any letters or symbols that are placed on the layer itself is far more advanced work possible. In this example the font is left exactly as typed and a minimum number of layers used.
Once you have the text you want to copy or duplicate the layer or layers. If you do not use a layer of paste just in front of other objects.
Align the fill style directly to the lines of force.
I will select the area with color so it is better to use colors with high contrast black and white as shown in this example.
If you work in a high-end software such as Photoshop you'll want to combine the contents of each layer by layer so that each section commensurate line of graffiti is one object and can be easily moved around.
Copy pictures or enough to cover the desired area and paste into your layout
At this point you can remove the white area in the text and the fire will be visible. You most likely will want to erase the image area of fire on the outside so please proceed to the next step.
Change the layer to the layer that contains the imported image while keeping the current selection.
Simply press delete to delete the image area that shows the back of your graffiti text.
The samples shown here do not use effects and has no particular colorscheme or be seen but the process is a cookie-cutter base can create a variety of 2D and 3D effects in a variety of applications.