Access this link: 

Complete the form provided by filling in the First Name, Last Name, Email Address, Leverage, and Balance

Tick the box to agree to the Terms and Conditions and click Open Demo Account

When all of the above is complete, you will receive your login credentials to log in on MetaTrader 4 via email. 

Kindly bear in mind that once all the funds from your demo account are used, you would need to open a new account. Demo accounts cannot be funded.