Now let’s bring in the main city element of our background on to the canvas. Found this stock photo on sxc.hu. Remember – you don’t have to shrink the image for it to fit entirely in the canvas. Our objective is that the main yellow building should occupy a significant amount of space in the canvas, towards the left side.
Once the positioning is done add a Vector Mask to the layer: Layer > Vector Mask > Reveal All
Now using the Lasso Tool (L) or simply Brush (B) , chuck out excess portions of the buildings (sky). You can use a Soft Brush(Hardness: zero) at the end to make things a little smooth.
Add a Gradient Overlay by going to Layer > Layer Style > Gradient Overlay. Use the same orange and purple colours as we had used previously. Blend Mode : Hue