Where to enter your SEP IRA contribution
https://ttlc.intuit.com/community/retirement/help/where-do-i-enter-my-sep-ira-contributions/00/26783
Use the Search box. Type in "self-employed retirement". Clicking on "Jump to self-employed retirement" it should take you directly to the Self-Employed Retirement Plans screen.
Go to Federal
Income
Scroll down to Other Business Situations
Self Employed Retirement Plans
or it might be under the Business tab in the Home & Business version.