Colossians 2:16-17—Let no man therefore judge you in meat, or in drink, or in respect of an holyday, or of the new moon, or of the Sabbath days: 17 Which are a shadow of things to come; but the body is of Christ.
Hebrews 8:3-6—For every high priest is ordained to offer gifts and sacrifices: wherefore it is of necessity that this man have somewhat also to offer. 4 For if he were on earth, he should not be a priest, seeing that there are priests that offer gifts according to the law: 5 Who serve unto the example and shadow of heavenly things, as Moses was admonished of God when he was about to make the tabernacle: for, See, saith he, that thou make all things according to the pattern shewed to thee in the mount. 6 But now hath he obtained a more excellent ministry, by how much also he is the mediator of a better covenant, which was established upon better promises.
Hebrews 10:1—For the law having a shadow of good things to come, and not the very image of the things, can never with those sacrifices which they offered year by year continually make the comers thereunto perfect.
One should be able to see why it is important to study the Old Testament; it helps us better understand the New.