Welcome
There is a lot of information here and many helpful people who can help you with your questions.
As for your specific question - this is not a lot of detail to go on. More information will help people to answer.
What about the current ECN process is not compliant? Are you talking about specifically user guides/service guides (aka labeling)? Is the scope of your update just the ECN process and change management or are you talking about writing the content of the user guide? What kinds of devices does your company make? Are you in a regulatory role or a quality role?
Your first step should be to understand what specific process you are remediating, and from there determine what the applicable requirements/sections of MDR are. There are a lot of requirements that will not be relevant at all for you, and other requirements that will be very important to understand. EU MDR does not really prescribe anything specific about your change control process so you will need to assess your own ECN process to determine whether it is compliant or not. Someone else at your company is almost certainly already working on MDR so it may be more helpful for you to find that person/people and ask for their help.