Many of the parts are already in core parts (resistors and capacitors and the like.) For the rest you will need to find a model number and search for and evaluate appropriate Fritzing parts (not all parts you find on the net work correctly.) First place to search is in core parts via the search icon at the top of the parts window. After that a google search for “fritzing part HC-SR501” for instance, will turn up a forum post (as would searching for it in the forum search bar but google finds more) that points to a part available on the net. Some of them such as the IR transmitter may not exist (the IR transmitter isn’t a sensible Fritzing part necessarily.) If you can’t find a part then you either need to make one or convince one of us to make you one.