Step by step (tedious 2+ stage process) to get inline images, and resize so they don't show up as huge in the post:
1) Write your post. Wherever you want your inline images to be in the body of your post, click the "Insert Image" button. That button is the far left option with the little mona-lisa icon, right below the BOLD icon. This will add the image tags[img][/img]
This is a placeholder for the next step and won't actually do anything yet. Leave the tags empty.
2) Attach your images to your post using the "Attachments and other options" button at the bottom. It doesn't matter what drop down option you pick, so probably just leave it as "End-of-post expandable thumbnail". (Yes I know most of those options say Inline, but it doesn't work).
3) Post your post. The images should be thumbnails at the bottom, with nothing inline yet.
4) Edit your post . Use the "Modify message" button on the right side of the post, with the little paper and pencil icon.
5) Copy Links. For each of the thumbnail images at the bottom of the post, click them to expand them to full size. Then right click and select "Copy Image Address". Now go back into your post and paste the address into the image tags you added previously. It will look something like this[img]https://www.eevblog.com/forum/section/post/?action=dlattach;attach=1850335;image[/img]
You could click the "save" button and be done, but your inline images will be full size and potentially huge and obnoxious. So be a good forum citizen and do the next step too:
6) Resize the images to fit the post: For each image tag, manually set a width option. Just change [img]
to [img width=xxx]
with xxx being the image width your want. 200 to 400 is usually a good size, but you may need to edit, save and check to see what it looks like. Repeat until your images are a good size.
So the full example would be:
[img width=200]https://www.eevblog.com/forum/section/post/?action=dlattach;attach=1850335;image[/img]
Note:
As pointed out below, using the "width" modifier on the image tag still downloads the full size image when someone loads your post. It's just resized in the browser. So if you want to be a stellar forum citizen and get 5 gold stars for effort, you can resize your images first before you upload them to save bandwidth.