As far as I know, you must have a certain high rating (which number I forgot) to be able to propose a problem for a contest, if this rating is reached you will be granted an additional button in your profile that give you option to propose a problem for contest.

According to How to set a round on Codeforces, Best problems usually come from the most experienced participants. We have limited resources for rounds reviewing, so to make the process flawless for writers, starting January 1st, 2021, the following requirements for problem authors will be applied:

• rating: 2100 or above, or
• was a writer in the past.

you need to be Master (impossible)

OR you have to be some authors homie so that guy wud add u as a coauthor (also impossible), from then on you can also author by yourself regardless of your rating

then according to @everyone, you will spend 1e69 days on queue