I want to get value from database with filter

I have 3 tables one is user table , 2 nd is doctor table ,3 is linked user to doctor i want to get values from customer table Firstname and Customer id.. Where condition is Doctor table mail id get from login

 

1)Customer Tables

114    tr                  re            ed@gmail           543

 

2)DoctorTable

 

DOCID   Name      Email  

 DR01      Ram       ram@gmail

 DR02      Krish      krish@gmail

DR03        sura       sura@gmail

 

3)User and Doctor Link

 Lkid    CustomerId    LinkedId

LK01     345                 DR01

LK02     543                 DR01

LK01      345                DR02

 

 

I want output like this

Firstname  CustomerId

xxxx             345

er                   543

 

linq query where condition is doctor table Email id in login please help me i am new one in Linq