Do you have template pack installed? If you do, all the files you need to edit are currently in your theme folder via FTP.
For example, yourtheme/members/single
To edit styles, template pack, or buddypress doesn’t add any styles to buddypress by default. You can add them by adding this to your current CSS.
/* Inherit the default theme styles */
<a href='http://buddypress.org/community/members/Import/' rel='nofollow'>@import</a> url( ../../plugins/buddypress/bp-themes/bp-default/_inc/css/default.css );
/* Inherit the default theme adminbar styles */
<a href='http://buddypress.org/community/members/Import/' rel='nofollow'>@import</a> url( ../../plugins/buddypress/bp-themes/bp-default/_inc/css/adminbar.css );
Then, of coarse, edit the CSS to what you like.