Can someone tell me how to write the PHP or direct me to a good resource for the following:

I have a page that shows my plans, each with an order button. The order button redirects to a page called register.php. Each order button directs to a different version of the register.php page depending on the plan selected.
After the person enters their information it is forwarded to my via email. What I would like it to do next is forward the client to a payment page specific to the plan chosen.
Any ideas?
Let me know if I haven't explained this well.
If there are any PHP gurus out there maybe you could PM me any I will give you a URL to check the pages I'm referring to.
Thanks for your help.

Just some feedback:

Why don't you incorporate an information verification page with billing, then have that e-mail you the order?

Most of the time I order stuff, I fill out a form, then it takes me to a verification page that summarizes the order I requested, and I then put in my billing info, and hit a button that takes me to a final confirmation page with all the dollar values (which also submits the order at the same time)and with all of the info that I can print out if I want a copy.

That way, you combine two operations into one, and the customer gets a confirmation page they can print out for their records.

Create a session or a coookie, which stores the plan id inside it maybe.

Or you could just use page.php?plan=$planid for each link, and then on register.php have something like this....

$planid = $_GET['planid'];
if($planid=="3"){
echo something here
}

MisterB, I'm trying to do all of this without ssl, so I can't collect any sensitive information until they are forwarded to either Paypal or 2Checkout.
Thanks for the suggestion Richard N. I will have a look at that.