Ok, in premiere first duplicate the clip you want to blur your ip in, so you have the same clip in layers 1 and 2. Lock the bottom layer so you don't change it.
Select the top layer, then in the project window select the tab effects. Open the video effects folder then Blur & Sharpen folder and drag Gaussian blur onto the top layer.
Scroll down from the blur & sharpen filters and open keying. Drag the four point garbage matte onto the top layer.
If it isn't already open, open window>effects controls.
In the effects controls window increase the blurriness of the Gaussian blur filter.
On the garbage matte filter there's an icon of a rectangle with a cursor next to it, click this. You can now drag in the corners of the matte to cover your ip.