Storing data on a traditional blockchain is quite expensive, on Nahmii, it's a bit cheaper but not quite an easy task storing data on-chain. A simple solution to these hassles is the InterPlanetary File System, the IPFS.
IPFS is a distributed system designed for the storing and accessing of files, websites, applications, and data. Using this as a storage, you don't need to store files on the Nahmii chain, but just the hash of those files on the Nahmii chain. This way, it's cheaper and easier to do so. Here's a reference to IPFS for more details.