function Undefined in go

Can any one help me why is the below code giving undefined:register error
I am trying to understand the call by reference and call by value.

package main

import (
"fmt"
)

type MyStruct struct {
name string
id int64
}

var (
s MyStruct
u int
)

func (u MyStruct) register() {
fmt.Println(u.name, u.id)
fmt.Println(u.name, u.id)
fmt.Println(u)
s.name = "vij"
fmt.Println(u)

}

func main() {

s := MyStruct{"deb", 11273090}
r := register()
fmt.Print("Inside Main****")
fmt.Print(s)

}

./prog.go:29:7: undefined: register