Creating a mod is very technical, so unless you have a lot of modding/coding knowledge, your not going to be able to create one.
Making a server is also a very tricky business, and you'll need to know how to port forward, as well as owning a powerful machine that is on 24/7 and has dedicated RAM for the server. Alternatively, you can use a minecraft server host, where you pay monthly and they do the hard work.
