How do I file my 2018 taxes?

Sorry 2018 is too old.   They only sell the last 3 years.  Even if you find the program you will not be able to update it or download any state programs you need.  You will have to go somewhere else like a local accountant.

Or If you have a simple return You can fill out the blank forms for free.

Here is the IRS 2018 Form 1040

https://www.irs.gov/pub/irs-prior/f1040--2018.pdf

And instructions  https://www.irs.gov/pub/irs-prior/i1040gi--2018.pdf

2018 Tax and EIC Tables https://www.irs.gov/pub/irs-prior/i1040tt--2018.pdf

IRS 2018  Schedules 1 thru 6 (only if needed)

https://www.irs.gov/pub/irs-prior/f1040s1--2018.pdf

https://www.irs.gov/pub/irs-prior/f1040s2--2018.pdf

https://www.irs.gov/pub/irs-prior/f1040s3--2018.pdf

https://www.irs.gov/pub/irs-prior/f1040s4--2018.pdf

https://www.irs.gov/pub/irs-prior/f1040s5--2018.pdf

https://www.irs.gov/pub/irs-prior/f1040s6--2018.pdf

Don’t forget your state.  And you will have to print and mail your returns.  So be sure to attach copies of your W2s and any 1099s that have withholding on them.  You have to mail federal and state in separate envelopes because they go to different places.  Get a tracking number from the post office when you mail them for proof of filing.