Someone help

I'm new, and I don't know how things go here, I wanted to know why my posts get deleted after three days, just recently I uploaded a picture and it hasn't gotten appealed yet. What did I do wrong?

Click "Wiki" at the top of the page. Pretty much everything you asked is explained there. Make sure to read "Uploading images" and "About the Moderation Queue", though you really should read everything in the "Site Rules and Guides on How to Use Danbooru" section.

The first of the images you uploaded (post #588849) simply wasn't very good art, what with the mismatched breasts, implausible shirt, and cut-and-paste genitalia; the other (post #590944) had (barely) passable art, but an amusingly bad hard translation and a watermark. Because neither picture was very good, none of the Janitors or Mods approved them, and they were automatically deleted after three days.

On the plus side, I think the latest one you've uploaded (post #593157) is of high enough quality to be approved (though be warned that my opinion doesn't count, as I'm not a Janitor or Mod), so you're probably on the right track now.

It's been over a day and still hasn't been accepted into moderation. I know I followed the rules. But nothing happened.

Some images take more than a day to be approved. The limit is three full days, quite a long stretch of time if you think about it.

Be patient, and if all else fails, try to appeal it in the deletion appeals thread. Just make sure you read the aforementioned wiki links before you do.

And DO NOT ask for it to be approved. (example:forum #30630) It would have the opposite affect on you.