Download the latest Mediawiki software from [1] and unpack it using $ tar zxvf mediawiki-n.nn.n.tar.gz Most probably this would create a folder by name mediawiki-n.nn.n. chmod 777 config (config is a directory present within mediawiki-n.nn.n)
Ensure Apache and MySQL are running and that you have created a database to be used for Mediawiki. You also have got the