How can I set a minimum donation amount

I have my form for donations right now i made the oppurtunites mandatory however soemone can submit the form with the other as 0 and not have to pay. is there anyway there can be mandatory amount not 0 and if choose 0 wont go through? 

Since it is not possible to set a minimum value for the quantity option in product fields, your setup would require creating the products outside of the payment field. 

First, you would delete your payment field and products.  Then, you would add your donation amounts as a radio button field and assign those options calculation values:

https://www.jotform.com/help/301-How-to-Assign-Calculation-Value

For your "Other" option, show a number field.  Number fields allow for limiting the minimum and/or maximum value entered in the field:

Make that field required and show it when other is selected:

https://www.jotform.com/help/57-Smart-Forms-Using-Conditional-Logic

Total everything up in a calculation field:

https://www.jotform.com/help/259-How-to-Perform-Calculation-in-the-Form

Then pass that total to the payment field:

https://www.jotform.com/help/275-How-to-Pass-a-Calculation-to-a-Payment-Field

I know that is a lot to take it, so I went ahead and made an example form for you:

https://support.jotform.com/form/63216798692975

You can clone it to your own account:

https://www.jotform.com/help/42-How-to-Clone-an-Existing-Form-from-a-URL

Then all you would need to do is set up the payment field and limits on the number field.