My employer only pays part of my health insurance premiums & balance is taken out of my paycheck after all tax deductions. How do I claim tax deduction for it in Turbotax

I have been using Turbo Tax Premier for several years. I was reading the following blog: https://blog.turbotax.intuit.com/health-care/when-can-you-claim-a-tax-deduction-for-health-insurance...

My employer only pays for part of my health insurance premiums & balance is taken out of my paycheck after all tax deductions. How do I claim tax deduction for it in Turbotax? Where do I need to enter this information? I am on W2.

Also, can I amend previous year tax returns to claim this for the past couple of years?.

Any help would be greatly appreciated.