you need the tuxwetter plugin, you can find it here in the database section, or install it via BluePanel.
To show a picture directly from a script without a tuxwetter config file:
# expand LD_LIBRARY_PATH because of missing libcurl implementation in NewTuxwetter Plugin
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/var/bin/tuxwet
/var/plugins/tuxwet/tuxwetter PICTURE=Title_VFB,"http://www.vol4you.de/Portals/20/800px-VfB_Stuttgart_Logo.png"
be aware that you have to start your script from flexmenu, to get and hold the focus for the RemoteControl from enigma.
For showing a list of pictures with tuxwetter the best idea is to create a config File for tuxwetter.
Have a look at /var/bin/tuxwet/tuxwetter.conf for examples.
To start tuxwetter with your own config file,
simply start tuxwetter with the path to your config file.
/var/plugins/tuxwet/tuxwetter /tmp/my_config.conf
here you can find some ( older ) script examples for using flexmenu with tuxwetter (Formel1Infos, EbayWap search, etc):
Übersicht alle Anwendungen fürs Flexmenu & Co.