These are not magic words that make God forgive you, they should be an expression of what you believe and want to do. You can make this change by simply praying to God in words like the following:

Dear God,
I know that I have not lived as you want me to. I have not loved you as I ought nor loved the people who live around me. I am sorry and want to change.
Thank you for Jesus. Thank you that he lived and died for me and rose again and is the Lord.
Please forgive me and help me to live as you want me to.
Amen.

There is nothing that you could have done that Jesus is not able to forgive you for if you truely turn away from your sin and turn to Him.