The lady went to the city to give her testimony. She said “Come, see a man, which told me al things that ever I did: is not this the Christ?” 
Her testimony consisted of two parts: 1) who Jesus is 2) what he had done for her. 
Testimonies are personal. If you were to share yours what would you say? Write it down. Record it. It’ll be an encouragement to you and could be exactly what someone else needs to see/read/hear. 
Scripture taken from: John 4:29