Open the code menu
In Blox Monsters, codes are redeemed in the in-game Shop. Scroll to the very bottom of the Shop menu to find the text input field.
Paste exact text
Codes are usually case-insensitive in Blox Monsters, but copy buttons reduce typos. Always use the copy button on the /codes/ page.
Claim before events expire
Active codes rotate every patch. Move stale codes to the expired section after each update.