Well, this is what I do, and it shouldn't matter what operating system you are using to do it.
1) Open a free account at
www.photobucket.com
2) Upload photos to your photobucket account
3) Once your photos are uploaded to photobucket copy the "IMG Code" that appears underneath the photo you want to post.
4) Come to Bladeforums and start writing your reply or new post as you would, and wherever you want to put the picture, paste in into your thread.
This is what it should look like to you before you submit your post, but without the '*'s:
[I*MG]http://i50.photobucket.com/albums/f327/stingray4540/IMG_0012.jpg[/I*MG]
And this is what it looks like when you post it, after you remove the '*'s.
This will also work if you have your pictures anywhere on the internet. You just need to know the URL of the picture itself, then copy and past the URL with [I*MG] and [/I*MG] on eather end of it, but without the '*'s. A way to find the URL of a picture on the internet is to right click on the picture, and select view image. Once you do that copy the URL that is in you address bar.
Here is an example. I searched the internet and found this picture, that was part of a blog or something I right clicked on the image and selected 'view image' and a window appeared with only the image on it, and this is the address that was in my address bar:
http://e-biscuit.com/images/uploads/voodoo-knife-display.jpg if you click on that link it should take you to the picture on the internet. Now if you just paste that link you just clicked between [IM*G] and [/I*MG] the picture will appear in your post, like this:
I hope this helps.