PHP PDO Cant Bind Params in Class

PHP PDO Cant Bind Params in Class

I cant get my code to bind the params to the Mysql Query, what am i doing
wrong here?
ERROR
Fatal error: Uncaught exception 'PDOException' with message
'SQLSTATE[HY093]: Invalid parameter number: number of bound variables does
not match number of tokens' in /Users/warren/Sites/Frame Work/Modules/User
Login/classes/db.php:34 Stack trace: #0 /Users/warren/Sites/Frame
Work/Modules/User Login/classes/db.php(34): PDOStatement->execute() #1
/Users/warren/Sites/Frame Work/Modules/User Login/classes/db.php(48):
dbConnect->get_contents() #2 {main} thrown in /Users/warren/Sites/Frame
Work/Modules/User Login/classes/db.php on line 34
CODE
<?php
include '../../../../config.php';
$dbUser = $config['username'];
$dbPass = $config['password'];
class dbConnect {
public function connect($dbUser,$dbPass) {
$this->dbUser = $dbUser;
$this->dbPass = $dbPass;
try {
$this->connect = new
PDO('mysql:hostname=localhost;dbname=totalrisk',
$this->dbUser, $this->dbPass);
$this->connect->setAttribute(PDO::ATTR_ERRMODE,
PDO::ERRMODE_EXCEPTION);
return $this->connect;
} catch (Exception $e) {
echo 'ERROR: ' . $e->getMessage();
}
}
public function select_table($table) {
$this->select_table = $table;
echo $this->select_table;
}
public function select_col($col) {
$this->select_col = $col;
echo $this->select_col;
}
public function get_contents() {
$stmt = $this->connect->prepare('SELECT * FROM :table');
$stmt->bindParam(':table', $this->table , PDO::PARAM_STR);
$stmt->execute();
$result = $stmt->fetchAll();
while($row = $stmt->fetch()) {
print_r($row);
}
}
}
$conn = new dbConnect();
$conn->connect($dbUser,$dbPass);
$conn->select_table('users');
$conn->select_col('site_name');
$conn->get_contents();
?>