This paper is intended to enlighten the curious minds on how to use cryptocurrency easily in our day-to-day life. What bitcoin really is? The relation between bank and the user, who has bitcoin, describes potential system design, basic payment method using cryptocurrency, the payment gateway and explains it in the simplest way, and finally the conclusion. Cryptocurrency is one type of digital virtual currencies that have not physically existed. This proposed research work is mainly focused on bitcoin, which is the decentralized digital currency, and it conducts peer-to-peer connection, to make it safe and secure than other digital currency types or hand cash. This paper has proposed an online E-cash scheme with a digital signature authentication cryptosystem that has the tendency to replace the traditional fiat currency, and bitcoin is used instead of the conventional currency and payment system. We can exchange bitcoin to E-cash and E-cash to bitcoin also. This system will find a new way to protect the users from unauthorized transactions in online and offline E-cash system.