The intention (niyyah) is a decision of the heart. You do not need special words, because actions are judged by their intentions (Sahih al-Bukhari 1). Scholars differ on when it must be made. The Shafi'i and Hanbali schools say it must be made in the night, before dawn, for each day of the fast. The Maliki school accepts one intention at the start of Ramadan, to be renewed if the fast is interrupted, for example by travel or illness. The Hanafi school allows the intention for Ramadan to be made until before midday. The safe way is to make it each night before dawn.
Suhoor is the meal before dawn. The Prophet ﷺ said, "Eat suhoor, for in suhoor there is blessing" (Sahih al-Bukhari 1923; Sahih Muslim 1095). So try not to skip it, even if it is small.
Iftar is the meal that ends the fast at sunset. The Prophet ﷺ said that people will remain in good as long as they hurry to break the fast (Sahih al-Bukhari 1957). Many Muslims break the fast with fresh dates, or dates, or sips of water, as he did before praying (Sunan Abi Dawud 2356). Then they pray Maghrib and eat a normal meal.
Check your local prayer times for the start and end of the fast, because they change by place and by day.