First, please don't post here if it isn't related to art. If it doesn't, I will move your topic to General.
I will move topics on the General-forum if they are, if I don't get them all, then you should PM me containing a link to the topic to be moved. Are you new here then perhaps you should consult the welcoming topic.
There are two ways of posting images on this forum: attachments and linking to external files. You may use either, but keep in mind that some schools (mainly in the U.S.) block lots of image hosting sites (for whatever reason), and thus the images hosted on those sites.
The easiest method: Attachments
Attachments are a feature of this forum engine. When you upload an attachment to a post of yours, the file will be stored on the same server as the forum. To upload an attachment: When you're posting, there is an "Upload attachment" tab right under the text area where you type. It's easy to find. Click that, browse for the file, click "Add the file", and then don't forget to click "Place inline". After this, the following code will appear in the textarea:
If the image is found on the web (for example in google image search), just copy the URL of the image. Pay attention to the end of the URL, it needs to end in a valid image file extension (.jpg or .jpeg or .png or .gif or something else, i wouldn't recommend .bmp though). Also, some sites protect their images from hotlinking, and you might only notice this after you've posted the image. In that case, it's best if you either download and re-upload the image, or find another source.
Where to upload to?
Simply use any free image hosting site, like http://imgur.com/ (recommended) , http://bayimg.com/ , http://imageshack.us/ or http://photobucket.com/ . Be wary that some of these sites give you multiple types of links, like HTML (NOT good for this site) or BBCode forum links, in which case you may not need to place additional [img] tags, or you may have to extract the direct link from some complicated link. In all cases, I strongly recommend to view your posted message afer posting an image, and check if the image appears correctly.
Also, if you are planing on presenting multiple unrelated pieces of art please place them in one thread rather than leaving a stream of threads with very little posts lingering on the first page. Secondly, please refrain from spamming long unrelated conversations in threads that are actively updated with art by multiple users, for example Lunar's poetry thread.