Generally when you are new to the site users will call you a multi meaning you had a banned account in the past and came back on a new account. Just simply ignore this and don't feed the trolls.
Report the post(s) and move on. If the users keep flaming you in your topics you can collect these posts and kindly PM a
Trade Moderator if it occurs in the trading grounds or a
Junior Moderator if it happens in a discussion forum.
If they are personally flaming you in your PM's, you can add the user to your
Block List aswell.
If you are feeling unsafe when trading, feel free to always request a Mediator for your trades. You can never go wrong with that and it will always ensure you the safest trade possible.
Feel free to shoot me a PM if you have further questions about this, or anything else :)
Thank you so kindly for this answer i will pm.