It takes next to no time to create your RealMe login. The best place to start is at the Government service you're looking to access. Enter your email address, create a username and strong password, answer a couple of security questions - and you're good to go. Once you have a RealMe login, a RealMe account is also created for you.
Through your RealMe account, you can manage the RealMe services you're using and see when and where you've used them. It's important you keep your details up to date. So, if you change your mobile phone number, for example, be sure to update that change in your RealMe account details - especially if you're using two-factor authentication.