every layer you add, you can adjust how visible it is wit a little bar.. from 0-100%
just select the layer on the right botom, and just above it it say's something like "opacity" or "fill" (don't know exactly cause I use a dutch version)
and on making pic's better looking... I often use "adjust colors/contrast" in photoshop (real easy)
you can pump up those color's even in the winter. the grass looks green again
here is a printscreen were you can get to these:
(Arrow)

and with the circel around it... that's were you can adjust theopacity
If you wanna learn certain thing... just look up at youtube there are 100+ how to's on there
good luck and have fun!