Everyone started somewhere, and we've all learned a lot a long the way.
1. You can perfectly write, as you enter a thread, that "Kaelyn had awoken early that morning to perfect her already perfect appearance", or "Kaelyn had just finished a most delicious dinner as she stepped out to enjoy the nightsky". Locations like the Compounds are usually free to have multiple threads in the same timeslot going if they take place in different tents, to allow for privacy.
2. Usually, name-dropping places and people is fine, just keep in mind what actually exists within the town of Ashford. But you can totally say "oh yes, on my way here, I visited this fabulous place called [name]", or "I met this knight from Dorne, [name], who is so charming and is the best jouster". (See below for a longer answer)
3. Roleplaying Games are all about taking on roles of what we aren't in our normal lives! I am certainly not an elven Paladin who rules her own kingdom, an 8 year old bastard girl in faux-medieval England, a former spy of MI5 who now is fighting British bureucracy as he tries to save the world from tentacled horrors from beyond space-time, a priestess of air who is a renowned hero, OR a 300 year old Sith on the path to doom.
Things like Wikipedia help covering the basics for most of us, and sometimes someone comes along with more info, but none of us are going to be all "omg you *don't* know how to hunt with a falcon?!". I barely have any idea how to hunt with a dog myself! So don't worry about it and feel free to gloss over details like how exactly falconry works!
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Regarding player-made locations:
In Play-by-posts, the location of the game (the castle or the town is the usual) tends to be structured enough by the GM that most players tend to not create new locales for the game. Since there is a meadow here with different tents, it is probably perfectly fine to add something like "a tent that serves Dornish wine", or "a stall with colorful paper-pinwheels for the kids". It is another matter entirely to add "and then this tavern here is a front for human trafficking and sacrifices to the Red God every sunday", because then you're entering on the territory of adding things to the world that the GMs have created that simply does not exist in the story they have attempted to set up for us to interact with. In some games, this works a lot better, but when in doubt, ask in the GM Question-thread. (This is of course advice I would bring on to other forms of Roleplaying Games, like tabletop and LARP, because GMs tend to put a lot of work into creating a gameworld. Some games encourage such inputs from the players, but those also tend to rely on playgroup or GM's permission and cooperation)