Gay Marriage & Proposition 8?

im a senior in high school and i have an argument paper on gay marriage and adoption due tomorrow. this paper has to be about 6-8 pages in length and i only have 2. i need you guys help. im for gay marriage and i need to argue and prove my point on why its allowed. i need to know what proposition 8 is, what harvey milk did for the gay community, and any extra info that could possible help me write this paper. thanks in advance !