I know you can buy tickets at the gate but can someone tell me exactly where? Like the gate to islands of Adventure or the gate to universal studios Florida (I would like to buy the 2 day 2 park one park per day ticket)

Ir would be better yo buy them through the webpage.

After the universal studios globe when you entered through the gate, look at right side for tickets window and kiosk for printing tickets.

Or in the lobby at a Universal hotel if you stay there during your trip. At the parks there should be a "guest services" counter.

You can buy tickets by calling the park you wish to visit or buy them online at Universal