how do you make a wordpress website have a register/sign in area on the main men

Hi

i wonder if anyone can help my client who i am creating a website for wants the following on added to a wordpress site

“make the website have a register/sign in area so we can create a contacts database”

i am not sure how to do this can anyone help? i am using colorway as the theme. i would prefer to have is on the main menu bar

any help would be great