Procedure selectors

So, i tried to make a procedure that teleports an entity/entities to a random location using: 

Set location of [Event/target entity] to x: (x+(Random(0,1)*10)-5)  y: y  z: (z+(Random(0,1)*10)-5).

I wanted it to only teleport certain entities, but i couldn't find custom selectors. (So selectors like:  Event/target entity, Source entity, but like a customizable one. For example : @e[type=enderman,distance=0..5]) Help is appreciated. (Sry if I wrote some things incorrectly, or if i was not nice, i'm not an english user.)

Note : I don't want to use vanilla commands, i don't want to make all the 10 trillion possibilities. (In my case.)