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no need to be confused. it's the same as before, just a more detailed system 😃
posting/voting/commenting is still the same.
give me specific questions if you have any 👍

I am confused by the changes in Steemit, I am no longer free to post and comment, I'm afraid my RC will run out quickly

Thank you for your answer @roundbeargames

posting and commenting has never been free anywhere :)
facebook/youtube/etc uses your data to sell ads. on steem you're paying with points (rc).
you can check your mana and rc at https://steemd.com/@santiintan
you have plenty right now 👍