Smart contract change for almost done

Hi, i am looking for expert that can modify my smart contract to pass pdf via this smart contract.
This was my requirement in start time, but almost done:
1. I need smart contract to create NFT for the certification(pdf)
2. the app calls back the blockchain addresss tx from API
Already compiled this using truffle and deployed compiled smart contract in rinkeby.
And developed node js script for api and deployed in heroku.
I attached smart contract zip, compiled smart contract using truffle, and node js script for api.
I need you to modify something in smart contract so that it will work for pdf passing using ipfs.
You can put nft-api in your explanations from your bid. otherwise your will not get reply from me.
I'm going to hire only expert for this. so don't bid if you are not having experience for this.
Thanks.