To setup your Exotel Account, the first step is to get an ExoPhone; given below is the 4 step process to acquire one (remember you would need ₹ 500 or more in your account to get an ExoPhone)
Step 1: Click on the ExoPhones tab in your Exotel Account
Step 2: Click on New ExoPhone button
Step 3: Select your region and choose the ExoPhone
Step 4: Click on Purchase and then assign the desired call flow
And you are set to go :)
Video reference attached.