To watch the Twilight movies in order, you have a few options. The most common order is the order of release, which is as follows:

1. Twilight (2008)
2. The Twilight Saga: New Moon (2009)
3. The Twilight Saga: Eclipse (2010)
4. The Twilight Saga: Breaking Dawn - Part 1 (2011)
5. The Twilight Saga: Breaking Dawn - Part 2 (2012)

Alternatively, you can watch the movies in chronological order, which is the order in which the events of the story take place:

1. Twilight
2. The Twilight Saga: New Moon
3. The Twilight Saga: Eclipse
4. The Twilight Saga: Breaking Dawn - Part 1
5. The Twilight Saga: Breaking Dawn - Part 2

Regardless of which order you choose, the Twilight movies tell the story of Bella Swan and her relationships with Edward Cullen, a vampire, and Jacob Black, a werewolf.