Help with community sells

I'm a 2 month old lolita with only bodyline I want real brand and I made this live journal at 1 in the morning TO BUY!!! (even though I have been lurking around for a year or so for lolita research [seriously I researched for 2 years after high school I can write a paper!]) but there is a terms I still don't understand! What is a pm when it comes to selling and buying on lolita community sites? I intend on staying with live journal and I would like to know how the feed back thing works as well. For a buyer it is less scary to see the the proof photos but I don't want the seller to freak because I have no feed back yet (when i get some it will be good!). Oh boy...

I have to get ready for church and by ready I mean EAT ALOT!!! Church is 4 HOURS!!! Every one is stirring it must be time. Thank you to anyone who can respond.