Reporting the long term gain sale of S Corp shares

if you sold the stock rather than its assets, you report the sale in the investment section of your 1040

The critical issue is determining the tax basis of your shares 

you do not need a 1099B. use the link to stocks, then the link to add investments. you will skip import. 

Click the stocks bonds (disregard that it says 1099b). then continue. for bank or brokerage enter "NONE"

Continue and answer No to are these employee stock. Answer no to more than 3 sales answer no to other types of investment. Yes to did you buy. select one by one and continue until you get to where you can finally start entering the details of the sale.  forget about the 1099B warnings

sales section  - select long or short-term did not receive 1099B (you may now understand why I told you to ignore the 1099B warnings. so confusing) 

type stock (non-employee)

description  - name of your s-corp

then dates acquired and sold, sales price, your tax basis (cost)