Michal, there is no such default functionality in our software and this will require custom code modification. But It would be much better to do this via creating a plugin. 
I'm not sure if there some existing plugin but you can try searching one in our Store.
In case there is no existing solution the best way is to find a third-party developer at http://www.oxwall.org/market/specialists.

I am also looking for a convenient solution that would help me with planning all my affairs. I want something simple and functional that will allow me to record tasks, meetings and other important events. I think that you need a calendar or planner that really works without any hassle. 

Having a paper calendar creates a special atmosphere. It is not just a planning tool, but something more. It is a personal space where you can leave notes, make sketches, mark important events. It is a kind of therapy to take a pen and write something important, feeling the texture of the paper calendar template and every glance at the calendar brings peace and allows you to focus on current tasks. It will not hide in the bins of your smartphone, like many applications.

In the year 2024, I am thankful for the invaluable opportunities to gain knowledge, joincrs com the meaningful connections that have brought richness to my life, and the steadfast resilience displayed in overcoming challenges,nurturing not only personal growth but also a deeper understanding of life's complexities.