open the tutorial and follow the steps
1)go to the Landscapes: intro to photoshop and Illustrator l page and open the part three :vectoring your landscape tutorial
2) prep your landscape simplifying the shapes of your layers (your foreground middleground and background) using image>adjustment threshold or posterize.
3) then adjust the coloring/ shading according the spacial categories of depth and atmospheric perspective lighter in the front the darker in the back. Image>adjustment Brightness and contrast *remember to hit Use legacy)
4) merge your layers down Layer>flatten
5) Apply a color to the landscape with image adjustment > color and hue (* hint press colorize )or image>adjustment Gradient map
6). copy and pasting the whole landscape into a NEW FILE in illustrator
7)in illustrator lock the background landscape layer and ADD A NEW LAYER!!!!!!
8) starting with the background begin to trace using the pen tool the shapes of your background, then apply a color that twins the color of your pasted image ( you can use the eyedropper tool for this)
9) add another layer and begin tracing the foreground!! and all the shapes in it!!! .