How do I use poe.trade to find out if I can add a certain craft to a weapon?

The suffix/prefix thing is bothering me. I want to find a damage over time fire sceptre and be able to craft fird damage. But the only 3 I've found always had something or something on it that prevented me to do that. And I can't figure out what I need to look for to NOT be on a weapon to add % elemental type damage to it.

you can search for items with open prefix and/or suffix along with other mods you want

official trade is better IMO. it takes a bit of getting used to from using poe.trade, but its faster and better search options. it also allows you to search for open prefix/suffix

Think with rares its 3 suffixes and 3 prefixes. the mods usually have a P or S to the left of them.