Here is a link to the instruction manual, and just under the place where it says Save These Instructions it tells you how to change the blade.
http://www.dewaltservicenet.com/documents/English/Instruction%20Manual/90520882,JS515.pdf
Fitting the saw blade (figure A)
- Hold the saw blade (9) as shown, with teeth facing forward.
- Push the lever (3) downwards.
- Insert the shank of the saw blade into the blade holder (10) as far as it will go.
- Release the lever.
There is a little lever where the base of the blade fits into the holder that you depress to release the blade...You can see a picture of it in the manual.
I hope this answers your question...if so, please take a aec to rate this post...thanks.