Thread:Talk:Multilingual MediaWiki/How can I edit / remove the Powered by MediaWiki image in the footer?

This section is unclear and has a dead link. I would like to translate the two lower right English language buttons to Welsh; I've also had a request to do it for the Irish / Gaelic Wikipedia. Can someone please write the instructions in simple fool-proof English? Here are the Welsh translations: Thanks!
 * Un o Brosiectau Wicimedia - A Wikimedia Project
 * Pwerwyd gan Wicimedia - Powered by Wikimedia