I used to be the same until I found out how to do it. It's actually pretty easy. I tend to search for pics through reddit.com and would select images that are from imgur.com. I also go through tapiture.com & sex.com as well.
1st) Find a picture online you like.
2nd) Control-click on the pic you want (or right-click if you're a pc user).
3rd) Choose "Open Image in New Tab". (This works with Gifs too).
4th) Copy the web address from the location bar on top of screen.
5th) Create a new post and click on the "Insert Image" icon (you can see it below circled in red).
6th) A window will pop up. Paste the web address in it and press the "OK" button. (Example below)
7th) Click on the "Preview Post" button to check if the link you pasted worked. (Some sites don't allow hot-linking from their websites). If you don't see any problems, click on the "Submit Reply" button to finish.
FYI, you can only link up to 10 pics or gifs in a single post. Hope this helps.