Add this on registration/index.php
$im = imagecreatetruecolor(65, 65);
$color1 = rand(0,900);
$color2 = rand(0,900);
$color3 = rand(0,900);
$background = @imagecolorallocate($im, $color1,$color2,$color3);
$white = @imagecolorallocate($im, 255, 255, 255);
@imagefilledrectangle($im, 0, 0, 65, 65, $background);
$texts = substr($reg_nick,0,1);
$texts = ucfirst($texts);
$font = 'modules/font.ttf';
$save_name = 'files/users/avatar/'.$usid.'.png';
@imagettftext($im, 45, 0, 16, 56, $white, $font, $texts);
@imagepng($im, $save_name);
imagedestroy($im);