If it's balance that you already have in your existing Steam account then that balance cannot be gifted anymore,
What you can do is look for other users ISOing games in this subforum and offer to gift them games using your balance inside their topics,
Keep in mind you cannot start FT topics for the purpose of selling credit or games that cannot be gifted, be sure to read through this topic before you start:
https://forums.d2jsp.org/topic.php?t=72779670&f=279