There are a couple ways to post pictures, but the easiest way is to upload an attachment.
You can do this from the post preview page. (For some reason there are more editing options on this page.)
So on this page, under the editable areas there are two tabs, 'Options' and 'Upload Attachment'. Click on the upload attachment tab, browse for your file, and then click "Add the File".
After you add the file then you will see it under the editable area. Click "Place Inline" to put the picture into your post.
Check it out! [attachment=0]angledView_onGrass.jpg
You can also post pictures that are hosted on other websites with the [img] tag. Thats usually what I do.