There are two ways to add an image to a post, Hot-linking and from your own image on your own separate image hosting site (like Imageshack).
You can't upload an image to this site from your computer or link to an image on your own computer.The way you display an image is to put the image location (URL) between the 'img' tags ([
img][/img])
Thus the structure is always [
img]URL[/img]
Hot-linkingThis is often frowned upon as it steals the bandwidth of the site where the image is displayed. This is often not a big issue for large organisations with their own servers but can be a problem for smaller users like personal bloggers who have to pay each time an image is viewed whether it's on their page or is being hot-linked to.
But here is how you do it in Firefox, Internet Explorer should be similar.
Right mouse click on the image you want to show and select copy image location
(in this example
http://news.bbcimg.co.uk/media/images/49558000/jpg/_49558331_soldiers304in_mod.jpg)
Come back to your post and put the cursor where you want the picture to appear.
Click the 'insert image button'

or type [
img][/img]
Put the cursor between the tags and paste in the URL thus
[im
g]http://news.bbcimg.co.uk/media/images/49558000/jpg
/_49558331_soldiers304in_mod.jpg[/img]
This will display as shown below

However some sites don't allow hot-linking and if this is the case some form of message will appear to that effect.
Some sites will divert hot-links to a very rude picture!
So be warned, if you're hot-linking PREVIEW YOUR POST!!!Hosting your own images.This requires you open an account with an image host like
ImageShack or
Flikr, there are other sites of this type. I have used ImageShack and it's OK. Both these sites offer a basic free package which you can extend by paying a subscription. I haven't extended my basic package.
Once you have an account you can copy (upload) images from your computer to the image hosting computer. Once this is done the image host gives you a location (URL) for the image. This is what you put between the [
img][/img] tags to display your image on this (or any other) forum.
So I have an image ht
tp://img823.imageshack.us/img823/7052/asmo.png
To display it all I have to do is add image tags around it thus (in fact ImageShack has display options and I choose the forum option so it adds the tags for me)
[IM
G]http://img823.imageshack.us/img823/7052/asmo.png[/IMG]
And it will display as below
Centring an imageDead easy just put the [cent
er][/center] tags or click the centre text button

around the image link [
img]URL[/img] thus [cen
ter][
img]URL[/img][/center] displays as
If you are having problems then post your questions here.