How to write a code in portal d365 ?

Scenario : I have made a custom customerself service portal and in that portal when i have logged in 

Supposing i am the admin i should be only able to see the "open the new case "other logged in  users shouldn't be able to see it

This however can be achieved using liquid can anyone tell me from where we can write the code or get liquid code tutorial 

For reference i have used the code but i dont know whether its correct or not 

% if user.roles contains 'Administrators' %}
    {% open a new case: 'Entity Form with Button' %}
{% else %}
    {% open a new case: 'Entity Form without Button' %}
{% endif %}

I will be highly obliged if someone resolves my query 

Thanks and Regards,

Ainee Ahsan