Mod on .json

[Adelious]

Hello I would change the mod on the .json ( on an other .json on my website ) but there are some information I dont understand :

{ **"id": "net.optifine:optifine:1.12.2_HD_U_F5",** "name": "Optifine", "type": "ForgeMod", "artifact": { "size": 2598821, **"MD5": "043ac1db6f7441ea4cf31bcb621aff0b",** "url": "http://mc.westeroscraft.com/WesterosCraftLauncher/prod-1.12.2/mods/OptiFine.jar" } },
What's the MD5 and where i found the ID after net.optifine:optifine
Ps: sorry for my bad english

[GeekCornerGH]

For anybody seeing this issue lately, just use Nebula