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.