I wanted to save 2 variables XP and rank but i know how because i want to use the info from one game to another game. please help i have been wondering how to do it and the tutorials didn't help. could you help?
That depends on what web service you are using to store your data. I can point you to a few ones:
Firebase Has a REST API, so it can be accessed via HTTP, but since HTTPService only supports GET and POST requests, you'll need to proxy requests through another service. You can set this up in a couple lines of code and upload it to one of the free hosting sites in the DIY section.
Firebase is what is called a Backend as a Service. They are primarily used for mobile apps and web apps, but are quite useful in the context of Roblox too. Google the term for some alternatives to Firebase.
If you only want the framework Firebase provides, but are willing to find hosting yourself, you have a few more options. Look into things like deployd and Hoodie. These generally require a bit more coding, usually in JavaScript, a language very similar to Lua.
If you are willing to fork over $5/month, try webscripts. Webscripts are small Lua scripts that run in the cloud. There is a free plan, but every script you write will expire 7 days after you write it, so it is only suitable for experimenting.
DIY. This is always an option. Several sites will offer you places to host your code for free, including OpenShift and Heroku. If you are willing to pay a small monthly fee, you can pick up a VPS for about $6 a month. These give you more complete control. I'd also recommend using Koding as a development environment.
Or, alternatively, just use Data Stores.