Go to your Module Manager, create a new Module and set the type to Custom.
Once done, open this module and you will see a big textarea allowing you to add any content you like.
You will need to set the position to bottom-d then save it.
Hope this helps
In the Joomla backend, go to:
Components (top menu) >> Contacts >> Contacts
Here you can add and edit contacts. There will already be a contact pre-added so you can simply open it and edit it to your liking.
I don't know the name of the module, but it's definitely a custom one.
Go to the Module Manager in the Joomla backend, and search for custom modules or module that belong to the bottom-section position.
Open the correct one and remove the image from the textarea
It looks like this image is in a Joomla Module.
In Joomla 2.5:
Login to the administrator area of your site
Select Extensions > Module Manager from the main menu
Look for a module in position bottom-section or similar - it'll probably be a Custom HTML module
In the HTML editor, replace the image.