You will need a global to set this up - at the moment you are only looking up the avatar of the logged in user.
Assuming your avatars are stored in /images/avatars/, and you store the filename in a column called 'Avatar', you will need a tag in your template similar to this:
The you need a global called 'avatar' like so:
my $in = $_[0];
my $user = $DB->table('Users')->select( ['Avatar'], {Username => $in } )->fetchrow;
}I adapted this from another global on one of my sites so hopefully it works for you 
.
Assuming your avatars are stored in /images/avatars/, and you store the filename in a column called 'Avatar', you will need a tag in your template similar to this:
Code:
<img src="/images/avatars/<%avatar($LinkOwner)%>"/>Code:
sub { my $in = $_[0];
my $user = $DB->table('Users')->select( ['Avatar'], {Username => $in } )->fetchrow;
}
. 