you can find Jesus spoken of or in images in every chapter of the bible, even in the old testament if you know how to look for it. Also, Jesus referred to the the old testament often in his teachings and confirmed many of the stories and accounts.
Old testament is still part of the word of God. But see, Jesus changed everything with his sacrifice for our sins. So the rules some of the rules given out to the Jews are now obsolete. Not of course the law of the 10 commandments but the sabbath rituals rules are no longer needed. Old testament is very valuable to every Christian and it will always be the Word of God
You can feel a change between the old and the new because…..Jesus made all the difference.