I already filed my 2024 taxes but I still need to file my self-employed taxes. Can I do that on turbotax?

Your self-employment income and expenses were supposed to be included with your personal tax return that you filed. 

You will have to amend the 2024 tax return you filed to include the SE income and expenses.

Before starting to amend the tax return, wait for the tax refund to be received or the taxes due to be paid and processed by the IRS.

See this TurboTax support FAQ for amending a current year tax return - https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-return/amend-federal-tax-return-current-year/L7eS6o1qh_US_en_US?uid=lfunevhk

Your self-employed taxes should be part of your 2024 tax return.  Since you already filed,  you will need to amend that filing in order to add the missing income. 

HERE is some information on the amendment process.  Depending on the version of TurboTax used for your initial filing, you may need to upgrade in order to include this income.  

Once you are in the amendment mode, you will navigate to "Business Income and Expenses" under Wages & Income.