How do i reset my security questions on my new ipad mini

If you can't remember their answers and you have a rescue email address (which is not the same thing as an alternate email address) set up on your account then go to https://appleid.apple.com/ and click 'Manage your Apple ID' on the right-hand side of that page and log into your account. Then click on 'Password and Security' on the left-hand side of that page and on the right-hand side you should see an option to send security question reset info to your rescue email address.

If you don't have a rescue email address (you won't be able to add one until you can answer 2 of your questions) then you will need to contact iTunes Support / Apple to get the questions reset.

Contacting Apple about account security : http://support.apple.com/kb/HT5699

When they've been reset (and if you don't already have a rescue email address) you can then use the steps half-way down this page to add a rescue email address for potential future use : http://support.apple.com/kb/HT5312

I Don't have a computer and I tried it on my iPad mini but it won't show the reset for rescue email or reset buttons

That means that you don't have a rescue email address, you will have to contact Support in your country to get the questions reset.

Contacting Apple about account security : Contact Apple for help with Apple ID account security

If your country isn't on that page then try this form to contact Support : https://www.apple.com/emea/support/itunes/contact.html

When they've been reset add a rescue email address for potential future use : Manage your Apple ID primary, rescue, alternate, and notification email addresses

Or if it's available in your country change to 2-step verification : Frequently asked questions about two-step verification for Apple ID