I was able to get my taxes from 2018 which I did not file. I have completed my taxes for 2019, do I add the taxes from 2018 or am i required to do a totally different process?

You NEVER combine the income from two or more different years on the same tax return.  So no, do not think about putting any of your 2018 income on your 2019 tax return.  The online software program is only for 2019-- no other year.

When you say you were "able to get my taxes from 2018"    it is not clear what you mean.  Do you mean you have your W-2's etc for 2018 and still need to prepare a 2018 tax return?  

Online preparation and e-filing for 2018 is permanently closed.

To file a return for a prior tax year

If you need to prepare a return for 2016, 2017, or 2018 you can purchase and download desktop software to do it, then print, sign,  and mail the return(s)

https://turbotax.intuit.com/personal-taxes/past-years-products/

Remember to prepare your state return as well—if you live in a state that has a state income tax.

When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s.  Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS/state received the return.

Note:  The desktop software you need to prepare the prior year return must be installed/downloaded to a full PC or Mac.  It cannot be used on a mobile device.

If you are getting a refund, there is not a penalty for filing past the deadline.  If you owe taxes, the interest/penalties will be calculated by the IRS based on how much you owe and when they receive your return and payment. The IRS will bill you for this; it will not be calculated by TurboTax.

When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s.  Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS/state received the return.

Since you have no AGI for 2018 in the system, you will not have a 2018 AGI to enter in order to e-file your prepared 2019 return.  You can try using "zero" as your 2018 AGI.  If that will not let you e-file 2019 then you have to print, sign and mail 2019.