If you want a resource pack for your server, open server.properties and edit  resource-pack to the path to that resource pack, which is the URI, such as resource-pack=C:\TEST.zip . It is optional, but is commonly used in minigames on other Minecraft servers, including Mineplex. In addition with this, there is resource-pack-hash, it is an optional SHA-1 digest of the resource pack, in lowercase hexadecimal. It's recommended to specify this. This is not yet used to verify the integrity of the resource pack, but improves the effectiveness and reliability of caching.