Sorry in advance for grammar and spelling mistakes :biggrin:
Can I give you some advices (only valids if you made it with Photoshop XD)? For the first image:
I would add a blur and a layer mask to the graffiti layer (or group of layers) so it will be more realistic.
I supose the blur has not secrets for you. With the layer mask and the 'render-clouds' + 'render-difference clouds' , you can give the graffiti itself a 'almost random' transparency effect.
Do you know how to make it? Backup the graffiti layer (or group) by copying it (you would want to hide it too). Then merge the group (or group the layer and merge it so the effects you're using are applied at all). Create a layer mask for this layer. Use the render-clouds once with the default fg/bg colors (i.e. white and black). Use then the diff clouds twice or more. Finally, adjust layer mask brightness and contrast and layer itself opacity.
Furthermore, if you change tha layer blending option to 'Overlay', although it will lose colorful, it seems better to me, more pro.
An example (a bit tacky, I know):
http://img267.imageshack.us/img267/1025/examplelayermask.jpg