Hello and welcome to PSG.
Here's one way to create the first image.
Find a suitable texture.
Find a suitable LA silhouette.
Open both in the same document.
Duplicate the texture layer.
Use a Levels adjustment to to make the bottom one light.
Use a Levels adjustment to to make the top one dark.
Create a new layer and add your text, in this case 2 letters L and A. It doesn't matter what color.
[ATTACH]77403[/ATTACH]
Open your LA skyline silhouette, it should be the top (uppermost) layer.
Use your Move Tool and Free Transform to position and size.
[ATTACH]77404[/ATTACH]
Turn off your LA text layer.
Turn off your LA skyline layer.
Select/highlight the dark texture layer.
Hold the Cmd/Cntrl key and mouse click the text layers thumbnail. This will make a selection.
[ATTACH]77410[/ATTACH]
Hold the Option/Alt + Cmd/Cntrl keys and mouseclick on the LA Skylines thumbnail. This will turn the selection into this.....
[ATTACH]77406[/ATTACH]
Now go to LAYER > LAYER MASK > HIDE SELECTION
[ATTACH]77407[/ATTACH]
You should now have the effect!
[ATTACH]77408[/ATTACH]
[ATTACH]77409[/ATTACH]
