like to know here how could I learn all the rules in this forum easily, quickly
Don't be quick to learning, because you may rush on it and missout some vital aspects you might have known.
Read the pinned threads on each board visited, then go through the forum rules and regulations.
Unofficial list of (official) Bitcointalk.org rules, guidelines, FAQ
https://bitcointalk.org/index.php?topic=703657.0and which is better for newbies to learn then posting or learn completely and then post ?
It's more better to learn before posting, so that you don't post garbage, after learning, you won't be stranded if what to post and how to post, make use of the search engine and only post when a question needs to be asked by you for further clarification.
and another question is - by maintaining clarity, how could i post in simple, clear, relevant and fluent manner ?
posting etiquettes
https://bitcointalk.org/index.php?topic=5184741.0#post_altgiveaway