Notebook Hardware and Upgrade Questions

HP gave me no instructions on the keyboard when I bought this.   None of the online manuals for this laptop show what all the keys do or how to select a certain function or character.   There is some limited info given, such as Windows shortcuts and function/action key descriptions.  The closest thing to a user's manual is a called a "Maintenance and Service Guide," which is not a basic user guide, and it doesn't include a complete keyboard "key."   So please do not refer to that in your response. There is a "User Guide - Windows 10" which only describes the actions keys and a few others.  The "Start Here" guide is no help.   I searched for "keyboard instructions" on HP Support and haven't found a keyboard guide.  Does HP have a guide that describes how to use all the keys?   Some keys have 4 characters on them, but I can't figure out how to type the other characters, after trying holding down the control, function, or alternate keys.  Some  key characters are painted in blue.  For instance, the =/+ key also has 3/4 in blue.   How do I type that?  Other uses of a key are abbreviations or symbols that I have no idea what they mean.   It's ridiculous that HP, et al sell their products without adequate basic instructions.   This came to a head today when I was typing an email and when I tried to insert other letters/words, it was overwriting the next characters to the right.  I looked for an "insert" key which I figured I'd accidentally hit, and found "ins" written in small letters above the "prt sc" key, but messing with it didn't fix the problem.  This made me realize that I didn't know how to use a lot of the keys, and didn't know what a lot of their functions were.  Thanks HP!