If you are a beginner, you're doing a great job.
Many aspects are quite subjective matter of a personal taste, like saturation. There are people, who prefer more saturated colors, and you can find known people publishing their blogs who start making photos with saturation slided +3 in their cameras. I prefer rather less saturated images like in your picture, which I tried to edit and shown beneath. There are some general advises regarding the framing, according to the rule of third, where it's usually better to put the main subject not in the center but rather somewhere in 1/3 of the hight/width of the frame. It's good, when while watching the photo, your eye can slide through it catching main subject, it's surroundings and finally the background. If you manage to catch some blurred foreground in edges or sides of the frame as well as background behind and even can make that subjects on the photo are sharp but become more and more blurred in some areas, it can make the photo "pop" showing truely 3-dimensional scene. As composition is the most difficult part of the photographer's job, I don't feel myself confident enough in this area to discuss it any longer
From technical point of view, to make subjects blurred, you simply set the number of the lenses' aperture as low as you can. If you move your focused subject more away from the background in the camera's direction, it will also lead to more blurred background. It helps to focus the viewer's eye according to your intention with the camera's AF focused area. It's also very often good to catch the sky not quite white but blue and the most dark areas not black but dark grey (if they are not really black of course). As it's in most cases the limitation of camera's sensor, you can fight aginst this shooting in RAW mode rather than JPEG mode and fix it later in postprocessing by increasing the shadows lumination and decreasing the highlight lumination and playing with tonal curve.
As all have mentioned before discussing the third photo, there was some problem with the setting focal length on your lens. You can read this article to see how the focal of your camera affects the image captured by the camera: http://photo.tutsplus.com/tutorials/photography-fundamentals/exploring-how-focal-length-affects-images/
and see this wonderful visual explanation: http://25.media.tumblr.com/tumblr_m3hp9gKTiO1qjltcyo1_500.gif
At last but not least, always observe your model's surrounding, like stones or branches to avoid situation "when you see it..." - 2nd photo
Anyway personally I think you deal great with your camera and only more shooting, reading, discussing and learning on your own errors will lead you to better work. And don't blame yourself, that your photos are not briliant (like other you see in Internet) just after downloading them from the camera - it's very rare not to enhance something or crop even a litlle in postprocessiing!. Ah, it's always easy to discuss someone's other work
Keep on shooting and make your model more smile