good job on going off auto... it too me much longer to do that than it did you!
i can tell that you've got an eye for the type of shot you are trying to capture. you are off to a great start! i would like to make a few suggestions for improvement as far as composition goes.
#1 seems out of focus. this would be a perfect shot if the stalks of grass were moved over onto the first third of the left hand side (rule of thirds) and if the stalks of grass were in focus. this has a nice peaceful feel to it.
#2 is a nice sunset capture. i like that you've used a lake to capture a reflection. the sky is so beautiful! however, all of the birds or stones (can't tell) in the water and the houses off in the distance, make the composition a bit too busy in my opinion. i think you could easily fix part of this problem by increasing the blacks in this photo so that it just looks like a silhouette of trees and you lose the houses (if that makes sense). it would also be nice to adjust the saturation of those colors in the sky to make them pop just a little more.
#3 is a bit too centered here. don't forget the rule of thirds
#4 is a very nice, simple composition. and the DOF here is excellent as well. i would suggest cropping out part of the bottom and right hand side of the photo to keep the composition in line with the rule of thirds.
i think you've got some really nice photos here and you're off to a great start. some of the suggestions i've made require some photo editing software. if you don't already have photoshop or lightroom, i would suggest checking out gimp software for now because i believe it's free! You can find it here:
GIMP - The GNU Image Manipulation Program