Selling Business Cards …

I simply want a form where customers can select 500 or 1,000 business cards, pay for these using payPal and fil in the appropriate information .. It's the PayPal aspect that I'm not understanding and how to set up custom items!! Please help!! Also, can PayPal accept credit Cards or can it simply collect money from other paypal accounts?? 

This can all be possible using our Payment tools. But I would recommend for you to use PayPal Pro because it has an option for credit card use. 

You may try to check this guide: Difference-Between-PayPal-PayPal-Pro

To add options and set up custom items, I would suggest you follow this guide: 

How-to-add-options-to-Payment-Forms

You can try to check this sample form. 

I hope this helps. Let us know if you need any further assistance and/or clarifications. Thank you.