Where am going Right/Wrong

Please really go for it. The more critism the better.
Taken with a 1000d and a Tamron 70-300.
Was trying to get my son in focus and sort of blur the backgroundish.

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I realize it's your son, but for me the first shot is would have been deleted - it's uninteresting and doesn't show much of your son's face (it's the eyes you want).

The second shot is better, but it seems to be out of focus and the highlights are blown (his left hand, cheek, etc.). In addition, you cut off his legs. Either go for the upper torso shot or get the whole body - cutting off legs at the calf is visually unappealing as is the swing to his right. Also, I realize he is in motion, but were you panning the camera with him as he swung? If you were doing that, it might have lent a nice stop-motion effect.

Finally (for me), I would worry more about capturing something interesting than getting the background blur. Subject isolation is more than just blurring the background - it's first about having an interesting and in-focus subject. Concentrate on the subject of the photo before you worry about the details such as "background blur."

I totally agree with you on all points, How could I have prevented the highlights getting blown?

I never thought of moving while he was swinging. Good Idea. That probably would have isolated him better.
I also reakon I was to close to him taking the picture, hence the chopped ankles.
Thank you

There are several ways to do it in-camera and in post.

What were your exposure settings? (shutter speed, aperture, iso)

Exif data
Camera Canon EOS 1000D
Exposure 0.003 sec (1/320)
Aperture f/4.5
Focal Length 70 mm
ISO Speed 200
Exposure Bias 0 EV
Flash Off, Did not fire
Orientation Horizontal (normal)

I was in AV Mode

I'm not an exposure expert, but a good rule to follow is to always try to shoot at an iso of 100. Being that it was bright enough, I think it probably would made somewhat of a difference in not over-exposing the highlights.

Also, meter settings are important. What did you meter off of? What was your meter set to (spot, evaluative, etc.) If you metered off a darker area, the camera, being in AV, would have compensated for the darker area (at least in my understanding of this). If you metered off a brighter area (which appears to have happened) the camera will compensate and expose for the darker areas while blowing out the brighter areas.

Shutter speed is important, too. As is aperture (obviously).