Good morning! If I sold land last year, is there a certain form that I have to fill out?

You should have received a Form 1099-S for the sale of the land.  The 1099-S is not entered on a tax return. 

The sale is entered as an investment sale -

To enter an investment sale other than from a brokerage account (1099-B), follow the steps below.

Click on Federal Taxes (Personal using Home and Business)
Click on Wages and Income (Personal Income using Home and Business)
Click on I'll choose what I work on (if shown)
Under Investment Income
On Stocks, Cryptocurrency, Mutual Funds, Bonds, Other, click the start or update button

Using the desktop editions -

On the next screen click on Yes
On the next screen click on Skip import
On the next screen, select Other and continue

Using the online editions -

On the next screen click on Yes
On the next screen, click on Enter a different way
On the next screen, click on Other and continue