This question is rather confused. What does the Alt key have to do with your requiring two backticks ` [not tildes, btw, they're ~ ]
Stack Exchange uses markdown for formatting, which means two backticks surround a code block like this. This is entered as
`a code block like this`
If you want to enter any markdown & not show as such, then you can escape formatting marks using backslash \
So if you want `two backticks without formatting` you type
\`two backticks without formatting\`
This & much more formatting help is available from within the text space, right above where you type your question or answer.