I want to reduce the pirce of crops for server play.

http://minetweaker3.powerofbytes.com/wiki/Mods:Harvest_Festival_Support

Thank you for your timely reply.
Actually，this is my first time to use it. Can you simply teach me how to do it?
For example , I just want to use "mods.harvestfestival.Crops.setValue("crop name", 20, 10);" this code to change some prices of corps, I want to know how to write and where should I put it.
Thanks a lot !

Read in to how CraftTweaker (Minecraft mod. You can find it on CurseForge) work :)