I'm just starting in the world of ux, I would like to know what a design system has I have read but I still don't understand, the only thing I have been able to do is create some components in figma and choose the letter size and message tables but nothing more, I don't know how to make the grid , so: c I would like to know about the experience of those who have built a design system I want to be able to help the front end. thanks in advance :)
welcome to ux.se! Unfortunately the question is rather broad, and doesn't have 'a correct answer'.
Design systems aren't built over night.
Typically when building a design system you'd have some idea of the multiple product requirements and variations. This might be done by auditing existing (or similar) products - taking into account platform, device, orientation, locale, presentation, brand, etc - all sort of high level aspects. Then break that down into standalone components and modules, before considering the reusable patterns, controls and other elements that are the building blocks. The actual colours, styles, fonts, etc are almost the least important. The latter could be changed easily (perhaps through a living style guide) propagating through the rest of the system.
It may feel easier and more tangible to start from the small details and build out, but really you need to research the big picture and work backwards, so that you know that the system you're designing is one that suits the purpose. Then you can follow the why of your design and the design system structure.
I often like to think of a quote by Eliel Saarinen:
"Always design a thing by considering it in its next larger context - a chair in a room, a room in a house, a house in an environment, an environment in a city plan."
If you're planning a city, don't start with the chairs.
It may be worth looking at other design systems to see why they might not work for you. There are hundreds of design systems out there, but few are really generic cross platform, OS-agnostic, multi-language systems. Personally I quite like IBM's Carbon Design System
I'd also recommend doing this with at least one or two other people from different disciplines to share the journey and get diverse insights.
Beware: Don't underestimate the maintenance effort of having a design system!