Erm... You need to create the directory ./var/www/html/moodledata with web server write access!
Except you don't because that would put your data files in your web area which is wrong. What you are really asking is "how do I install Moodle". Can I suggest you re-read the installation documentation, particularly this bit...
Creating_Moodle_site_data_directory
If you have problems or any of it doesn't make sense we'll help!
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Failed to login to my moodle
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