Fixing the over Defined sketches......
when you face this problem a pop-up box opens.
choose the second option as in the image below and hit "ok"
solidworks will now notify you about the error.
click on that
Solidworks "SketchXpert" will open in your feature manager area.
click on "Dignose"
clicking on dignose will show you all the possible fixes for you sketch.
Browse & Accept as shown.
now your sketch is error free. and you can make more changes to make it fully defined.
Now Mr Stephen Nyberg will help you to make your sketches fully defined. tutorial here: http://grabcad.com/questions/tutorial-tip-fully-defining-sketches-in-solidworks-splines