first, make sure the blinkie is hosted on an image hosting site. I personally use imgur but there are lots of alternatives. edit the part of your profile you want the blinkie on, and input this code:
<img src="(put the address of your image here)" width="(if you need to adjust the size of your blinkie then put the number of pixels here. if not, you can delete this part) px">
I hope I was able to help, if you need extra help let me know