i just bought a secondhand ipad mini but cant set it up it seems to have my very old email address in it and i dont remember the password for that. ive been using a different one for a few years now. how can i get it to use my current address?

I am confused on your question. You just bought a second hand ipad. So, you are not the original owner but somehow it has your old email address (Apple ID address?) on it. And you forgot the password for that ID. See if this helps recover your password: https://support.apple.com/en-us/HT201487. Once you get into it, I would erase it and restore it as new to enter the information that you want.

In addition to what kb1951 said, I too am confused and don't understand how a used iPad Mini could possibly have come with your old email address tied to it. If as I suspect, it's tied to the previous owners Apple ID and Password, you cannot use the iPad unless you can get the previous owner to remove their Apple ID from the iPad. If you don't know them or can't get their assistance, the device is useless to you. Apple won't help you and we can't help you if this is the case.