ok, this is how you do it:

1) resize your images to be 400 pixels wide in a program like photoshop (go to the Image menu and choose Image Size). If you want people to be able to click on your image to see a bigger version, also save a version that is 800 pixels wide. Make sure the image is at 72 resolution (this can also be done under "Image Size". Also make sure there are no spaces in the file name.

2) Create an account with a free online web hosting service like photobucket.com. You can upload your images to their site, and then link to them on other sites like this one. Then all you have to do is copy the img code provided for you right under your image and paste it into your post. Preview your post first. You should see the image. Then post it!

i can post about linking to larger images, it's a little trickier.

hope this is helpful.

--sarah