I use PostImage to store photos for sharing/hosting online. It's simple. For example, here is a photo I have uploaded to PostImage:
At my account at PostImage, when I look at any given image, there is a menu of items across the top of the page. One of the menu items is Share. When I click this, I get a list of different links to use elsewhere in the Internet. I choose "Hotlink for forums" and the link is copied to my computer's clipboard. Back here, I just click in the Reply editing window and click Ctrl-V to paste it.
Most if not all hosting sites have similar features.
If you chose to use the Insert feature, click Insert, then click Insert Image. In the dialog box that opens, paste the URL of the photo you want to share into the Source box, then click OK. The website should now show the image in your post. Here's one I just found with a quick web search. I clicked to view the photo, then copied the URL from my browser's Address box: