One offer per topic. Put the price in HITCOIN, the delivery note and what is included in the first post. Offer means you provide something, Wanted means you are looking for it; pick the category so the directory filters work.
Agree in the replies. The Pay button on a topic sends HITCOIN from the wallet you are logged in with straight to the other member and records the transaction in the topic once the chain confirms it. A recorded payment moves the topic from Open to In progress; the poster moves it to Done or Closed when it ends.
When the deal is delivered, both sides leave feedback: positive or negative, with the amount and a line about what happened. That is the Trust number under every handle and on the profile. One entry per member per topic.
No escrow yet. Pay after delivery or in parts, and read the other member's feedback first. A member with more negatives than positives shows in red. Report a bad deal to the moderators from any post; proven scammers lose posting rights.