Try using your prt scr key (print screen) when map is in web browser, to copy it and paste into paint (if running WIN 7) WINXP will copy to other programs. Crop and save in jpg file format.
If the buttons don't show on the quick reply (TreasureNet message box) click the "go advanced" tab, then scroll down to tab "manage attachments" click it then multiple image uploader should appear. Select your image files, click upload and wait. Make sure to use the right upload button. Click close at top. Now you are ready to post your maps.