Find collection by categories and dates

I have a model called “Posts” and want to sort them out and get
collection based on categories and dates.
For example,

  • “today’s” “posts” in “category 1”
  • “yesterday’s” “post” in “category 2”
    or something like that.

Could you give me some hints how can I do this?
I don’t know where to start :frowning: