如何创建和使用PayPal沙盒帐户？

我绝对新手到PayPal的API，我需要给贝宝在MVC 4存储整合。我一直在阅读了很多在线教程，似乎你需要创建贝宝沙箱现场两个虚拟帐户（买方和卖方）。我认为，贝宝近来做了重大更新他们的开发者网站，我不能明白我应该在哪里创建这些帐户一位，他们将免费或不？是否有任何更新的资源仍可使用新的PayPal更新站点那里是否有效？

I am absolutely novice to PayPal api, I need to integrate PayPal in an MVC 4 Store. I have been reading a lot of tutorials on-line and it seems that you need to create two dummy account (buyer and seller) on PayPal sandbox site. I think PayPal have done a major update to their developer site lately and I cannot understand one bit of where should I create these accounts and will they be free or not? Is there any updated resource still valid with the new PayPal updated site out there?