don't know where to start x_x

[Musano 19]

hi everyone

i want to replace my character face with external one (blender make mesh ) and i don't know where to start 

this might sound so dummy , but i've been googling so much and felt lost  , i've watched tutorials about customizing character with CK but the step where i can import external mesh then editing it is very confusing and sounds like it needs basic knowledge of something , and to be honest i don't  have time to learn unnecessary things if idon't need this mission. 
so anyone knows what is the arrangement of  steps i need to learn or do  ( from mesh in blender till importing in racemenu ) to reach my goal  .

[SavrenX 10,319]

What you ask, require explanation like short novel. I doubt somebody want explain it so complete ( if they can do it too ). Not to mention making malehead.tri from new meshes. Even Dizona and Dem can't do it complete like vanilla. The easiest way, maybe use high poly skyrim head ( as base ) and reshape it in blender. Using new meshes, different vecticles, ect really complicated. Making expression for racemenu slider kind nightmare actually.