Good effort, the first image is the best, but as mentioned clone out the stick so the boy isnt connected to the background.
I would recommend on getting a different background, a plain colour normally works best.
There are two main styles of portrait photography, high key and low key and they will require different techniques to achieve.
Low key images like these two are normally dark and moody, any light that does fall on the subject is usually not softened with diffusers or softboxes
High key images tend to be much brighter (most tend to have a white background) and usually with softer light.
You can use light to alter the background, as the light falls away it will change from white to grey and eventually black. Therefore by using only a single light on a background instead of two it is possible to create gradients like i have done in this pic