I am opening a minecraft class folder with notepad++. But whenever I open it, it just has a bunch of boxes that say Nul, DC1, SO, SOH, FF, STX, ect... On guides I see that the class file opens just fine, what am I doing wrong?
You are trying to edit a compiled Java class.
It's not a text file, so you can't edit it with a text editor. You want a .java
file, and I don't believe Minecraft is open source.
Check your guides again, you've likely strayed from the path on which they were intending to lead you.