Vaccination Program in Shell Programming (Linux) Error [closed]

I am having errors in my program please guide me to resolve my program errors enter image description here

Vaccination Program in shell programming (Linux) :- if age>=18 then it will ask you are vaccinated if vaccinated then it will ask first dose or 2nd dose if first dose then it will tell go for 2nd dose if 2nd dose then it will print congrats. if age <=18 then print you are not eligible but wear mask.