First of all, may I suggest forgetting about XML and going to JSON? Whoever writes the code for the server is going to be much happier - parsing JSON is orders of magnitude easier and more efficient than XML.
After that - you will need something to store the data (some kind of a database) - either on the server or the cloud (it is usually cheaper and easier to store it in the cloud, if it is a small database - AWS and most other cloud providers have a free tier that makes it cheap and easy to store in the cloud - without the hassle of running a database on your own server. Finally, there needs to be some kind of a program to parse that data and store it in the database - that's usually something that you will need someone to write it for you.