modinghelp

I tried making a mod using cp. I tried adding a keg recipe but it says it don't knows the id "Keg", what am I doing wrong

I basically need major help in figuring out how to mod. I've watched videos, read through the forums here and I'm stuck. Maybe a bit afraid to mess up my computer. I have downloaded SMAPI. I tried downloading via nexus mods and nothing worked for me. The mod folder will not show up for me...