How can one call people to Allah in a foreign country whose language one does not master, and what English books are available on the Prophet's Biography (Seerah)?

Summary of the answer: If you are unable to communicate in the language, then invite people through your uprightness and actions, such as excelling in your work, honesty, and trustworthiness. Many have embraced Islam because of silent callers. Among the important books translated into English about the Prophet's biography is "The Sealed Nectar." It is advisable to consult Islamic centers to benefit from their expertise in Da'wah.