Go to Content Paradise. 

Create an account if you do not already have one.  CP accepts the 4 major credit cards.  They do not accept PayPal.

Sign into your account.  Go to the Software section of the store. 

Locate the version Poser Pro 2012 you wish to purchase. 

Click on add to cart.  You will get a pop up asking you if you want to continue shopping or if you want to check out. 

If you want to check out, click on go to check out. 

It will take you to the checkout page. 

You will see the application on one line and an extended download listing on the next.  If you do not want the extend download option, go to the left. 

There is a garbage can icon.  Click on it and it will delete the extended download.  If you do not buy the extended download option, you will have only 30 days in which ot download your order.  Smith Micro Systems does not give lifetime access to your purchases nor do they reset expired downloads.  If you want access to an expired download, you have to purchase the extended download service.

Be aware.  If you buy Poser now, you will not get it for the pre-release price.  I don't know if it's on sale at the moment but I do know the price will be higher than it was in September.

Once you have everything in your cart you want, go through the checkout.  If you are using one of the 4 major CC's, you shouldn't have a problem unless you are from certain regions.

If you don't mind my asking, where are you from?