PLEASE NOTE: If you're posting personal content (especially external, like from your own website) and want to include high resolution images here on the forums, please link to them externally from your own host. If you're trying to attach source code, a PDF or low-res images used in examples, you can do so in the following manner:
Attachments_Tutorial_01.jpg
If you don't see the "files" bar, click "PREVIEW" and it should appear.
Attachments_Tutorial_02.jpg
Once it does you can either drag images onto the bar or click the bar to open the file select dialogue. Once the images are loaded, you can select the "INSERT" button (green arrow) to insert the image at the current cursor position. You can also select the "X" button (red arrow) to remove the attachment.
Attachments_Tutorial_03.jpg
Once you click insert, you're prompted to enter optional dimensions. I usually do this to the original, but when linking external from my main size, I usually limit the image to 640, unless it has text that can't be read.
You're only allowed 4 attachments per post at up to 1MB (total for all), so you may have to edit images to get what you need (see some of my posts). I usually limit my uploads to 640 pixels wide (640x480), but you can go a little more. The forum will resize them to fit within the viewable window, I believe.
As a favor, if you have your own "permanent" hosting, please link from that. If not, please be conservative with attachments. Thanks!
Thanks!