If you've never refilled a toner cartridge it's not hard.
Here's a tool you can buy:
https://lasertekservices.com/blogs/default-blog/refill-tool-creating-a-fill-hole-on-the-toner-cartridge
OR
You can just take a piece of 1/2" copper pipe, heat it with a torch or over a gas stove (holding it with a pair of pliers of course) and then using the heated tip of the pipe to melt the hole).