I entered information from a 1099 - R into a W2 form ... do I need to change the form and if I do how do I do it ?

Yikes.  Did you file your return yet?  If you have not filed then Delete that W2 and enter 1099R here,

You can just type 1099R into the search box at the top of your return, then find and it will give you a Jump To link to go right to it.

OR Enter a 1099R under
Federal on left
Wages & Income at top
Then scroll way down to Retirement Plans and Social Security,
Then IRA, 401(k), Pension Plans (1099R) - click Start or Update

If you get the screen of partners you can import from click the bottom circle for I'll type it in myself - Continue
The next screen should be What Type of 1099R is this? With 4 choices. Pick the right kind you have.
And on the same screen you pick which person it is for if you are married.

You need to delete the W-2 that you entered incorrectly and then enter the 1099-R in the correction section of the program.

To enter, edit or delete a form 1099-R -

• 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)
• Scroll down to Retirement Plans and Social Security
• On IRA, 401(k), Pension Plan Withdrawals (1099-R), click the start or update button

Or enter 1099-r in the Search box located in the upper right of the program screen. Click on Jump to 1099-R