Fresher... need some help please

How would you implement the following rulesA email to staff if someone gave a donation of more than $500 (assuming that the donation is in the opportunities table)
Add a membership level to a contact – define the process you would use to assign the membership start and stop date in a custom object
i. Memberships based on

1. You have a membership level, membership start and membership end on the contct

2. $500 and over – Gold Member starts the day of the closed opportunity or extends for one year from existing membership ending date

3. $250<$500 – Silver Level starts the day of the closed opportunity or extends for one year from existing membership ending date

4. Lifetime membership $5,000 and over – membership extends to 2020

Define how you add the following fields
i. Highest opportunity every

ii. Last opportunity date

iii. Last opportunity date last year