There are two ways to say "to be" in Spanish, but they're not interchangeable. The two verbs are Ser and Estar. Here are some links to learn more about the second, and you can also explore the difference between Ser and Estar.
Online activities from the Exprésate textbook
Practice with Estar and Prepositions
Online Dictionary, Verb Conjugator, and Language Forums
Full conjugation of Estar
Video interviews, podcasts, and grammar explanations
Online Grammar Lessons with worksheets
Quizizz Class Practice - Start Game - Student Login
ESTAR is one of The Big Four. Practice them on Quizlet.