how do enter the wp-content/plugins directory?

I have installed word press with my godaddy account. now I would like to change the view and feel of the blog, to add plug ins and so on. the help tells me that i should upload the plugin file into my wp-content/plugins directory. but where is it? do i have to change settings within godaddy? or where is the hidden way to upload new things to the database (same for a new background picture). THANKS A LOT for some information.