PHP-General - Preventing repetition of a Form

I have a program [*pseudo code*]:

if(!isset($_REQUEST["welcome_already_seen"]))
{
initialize variables
}

$errors_array = array();
if($_REQUEST["welcome_already_seen"]== "already_seen")
{
check_data();
if(count($errors_array) != 0)
{
show_errors();
show_welcome();
}
else
{
show_welcome();
}
}
if(!isset($_REQUEST["welcome_already_seen"]))
show_welcome();

switch ( $_POST['next_step'] )
{

case "step5":
{
do something
form
next_step = step8;
/form
}

case "step10":
{
do something
form
next_step = step5;
/form
}

etc...etc
} //end switch

function show_welcome()
{
do something
form
next_step = step10;
/form
}

The show_welcome() persists in each step.

1) Enclose your code in [ PHP ] tags. See the sticky at the top of this forum.
2) Use a session variable.

do i need some modification in this code?

Yes. You need to set up a Session and set a variable to determine if the form has been previously displayed or not. Keep in mind that PHP is stateless. Once it ends it knows nothing about what it may have previously done.

i have a high regard for your thoughts.