Click the search icon in the top right and search for "HSA" and click the jump link. This should bring you back to your HSA summary where your distribution will show. Click Edit and follow the prompts until you get to a screen that asks "Did you put money into an HSA" and then you should get the screen below. The second line (see attached screenshot) is where you can enter your contributions outside of the payroll deduction process.
It's not clear from your question if you also need to amend your return to report this contribution. If so, you can follow the instructions below to start the amendment process and then when you get to the screen asking you what you want to amend - use the steps above to enter the contribution.
https://ttlc.intuit.com/replies/3288565
