Hey there Sir Mister and welcome to PokeCommunity :D To trade really, all you have to do is to find someone who has something you want, and contact them about it to work something out, be it by PM, VM, or in their thread. However some people and areas have rules about how they want to be contacted, so be sure to read up on that to prevent any accidental problems in the future. Hmm, since you don't feel ready to set up a shop yet, I'd say don't worry about it for the time being. When you are ready, feel free to post here again, ask a mod, ask for help in the
Trade Corner IRC Chat Channel, or even PM/VM me if you'd like. If you'd like to look at some guides and outlines to help you understand what you'll need for a good shop, consider checking out
TC's Rules and
TC's simple CSS Guide.
To answer your questions:
1) You cannot make a thread just based on a few things you are looking for. The Quick Trade Thread is found
here and is used for small posts about what you have to offer or want that does not warrant it's own thread. So if you're looking for or offering just a few things, post it in there. Be sure to read the rules though! A lot of posts get deleted for not following them.
2) In general, people except things that seem to equivalent (i.e. random Pokemon for random Pokemon, Shiny for Shiny, or Event for Event). Of course you could always just make an offer to that particular person and see if they'll accept your offer. If they don't, just try again with other Pokemon. A lot of times this is solely based off your own judgement and the judgement of the other person. Sometimes people will list what they want but when they don't, I'd suggest asking for what they're looking for first. If it's something you don't have, don't feel discouraged! Just make an offer and see what they say.
And don't worry about the questions, they are all legitimate questions I wouldn't mind answering. It's like the sayings I've heard, "There's a time and place for everything" and "There are no such things as stupid questions, just stupid people" (not that you're stupid of course). In any case I hope you enjoy your time here on PokeCommunity and here in TC.
We are the best section here of course. If you have any further questions, don't hesitate to ask them here or just shoot me a message if you want. > 3<
[Also the (technical) 1000th post in TC DCC \o/]