That ALL depends from which site you wish to post "gifs memes or pics from" from. I'm using a site now where I can just "copy & paste" pictures, gifs etc.... No URL needed.
For example, if you use the "Tenor" site. All one needs to do is click onto the gif and a box comes up "copy URL?" Click onto it and it automatically copies the URL for you. All you have to do then is go on this site and paste URL in the box. Also, if you have pics of your own on your computer, open them up on a web page then right click and you'll see that particular picture' URL.