When you start a post, look for the 'Manage Attachments' button a little ways down below the text box. Click that, then a dialog box will appear where you can 'browse' for your pics and then 'upload' them. When that's done, close that dialog and click 'preview post' and your pics should appear as 'attached thumbnails' at the bottom of your post. I've attached one of my purty little white widows as an example. ez-pz. Now you try.
also when viewing your pics, view in microsoft office picture manager, then you can resize to 600 x 800, i suspect thats the problem you are having, exceeding the size limits?
^ Yup. Or you can right-click on a jpg in Explorer and click 'Resize Pictures'. "Large" (1024x768) works for me.