1. The question has nothing to do with the topic - so please register and tell us which one you want answered.
2. Any place that sells things for phones - eBay, Amazon, Alibaba, etc. They come as a single piece or as a short cable - your choice. (If you have a case on the phone, a single piece adapter may not fit - it's normally wider than a Type C connector. The cable, on the phone end, is just a Type C plug, so it fits.)
To download a .jpg file to the phone, if you're using a web browser, just tap the Download button (if there is none, the picture isn't for downloading). From a PC, connect the phone to the PC, open the "Phone" in the PC, open the folder that has the .jpg file, drag it to the phone and drop it. (If you want it to go to somewhere on the phone other than sdcard, open that folder first, then drag the file to that folder and drop it.)