This is a common trouble for most people. Most people think that you can just import the image from your computer database directly to the post, but there's no way you can do that. You need to import a photo from your computer to an image hosting site, get the link code from the image hosting site, THEN post it on your forum post. I usually use photobucket as my image host.
If you want to post a picture on a post, like for example, this:
(This is from a post in the funny Jrock picture section)
What you would need to do is:
Whether you do or do not have an account on a image hosting site such asPhotobucket, flickr, or tinypic, you can just upload a picture from those websites.
How to do that is: (for photobucket)
Pick a picture, any picture
Then go to the tab where it says "share" and click on "post to a website"
A box of options will appear and click on the "Get link code" tab and there will be links that you can copy.
For the picture to post correctly on the forum, you would need the correct code. There are many different varieties of codes that serve for different purposes, but for a forum post, go to the "IMG for bulletin boards and forums" section and the first link that says "full size" next to it is the link that you need to copy.
Note: make sure you fully highlight the link in order to copy all of the code instead of half of it. Also make sure that it is the "full size" code that you are copying because if you copy the "clickable thumbnail" code, it'll be a clickable link to your picture and the picture might not show up directly on your forum post.
The clickable thumbnail would look like this:
the thumbnail is basically a URL link and it just gives you a link to the picture when you click on it. So if your posted picture looks something like this, it means that you copied the wrong link.
Once you highlight the correct link, right click on your mouse and select "copy" on the pop up box. Then paste it directly on your message box in the forum by right clicking on your mouse and selecting "paste".
And after you've finished pasting the link code for the picture and have submitted/completed your post, then your picture should be shown like this on your post:
If it doesn't work out the first time, try again. It took me a while to figure out how to do it and I even had to have someone help me.
Oh and also, this is how you post a video too ;D *hint hint* *wink wink* 0.<