Sure, when you are posting something, under the text box theres some text that say "Additional Options", click that. It will bring down an "Attach" option, just click browse and select the picture of your bike you would like to upload. The maximum filesize is 75kb, so if your picture is too large check out
this Image Resizer thread that explains how to resize your images, which will decrease in file size.
If you have any problems, tell me.
rl.