You are going to need to provide more information for us to help. What programming language are you using? What type of calculator are you using? What exactly do you mean by random equation generator?

Sounds like you are trying to make a TI-BASIC program. Sorry to disappoint you, but there are almost no i/o routines in nspire BASIC, let alone graphical ones.
You might be able to use dialogs though. Also, if you are willing to go PC-side, there are some utilities which allow you to create Lua progarms for your calc.

As far as I know, for lua You've got 2 options: You could get the student/teacher software and do it from there. Unfortunately this approach costs real moneys ( ), but you get an IDE-like environment with an emulator and all. On the other hand, you could get a third party tool (like Luna, for example) which will convert and package your lua files into a .tns file. This article on hackspire gives a pretty nice rundown of the methods you could use and also links to a page with documentation of all the API's on the nspire: https://hackspire.org/index.php?title=Lua_Programming. If you are new to programming in lua, I'd also recommend you to first do some tutorials on a computer instead of jumping straight into the nspire. There's a lot of really nice lua tutorials on the internet. Aside from that, you will also need to learn about how event-based programming works, since this is the model that the nspire API uses.
Good luck with your program!