How can I help teach a Christian girl who wishes to embrace Islam, when I do not have sufficient knowledge?

We congratulate you on your call to Islam and remind you of the Hadith: "For Allah to guide one man through you is better for you than possessing red camels." You must exercise caution when inviting women via the Internet or directly; it is preferable to invite them through your wife or one of your mahrams. If you are unable to converse and debate with Christians, do not argue without knowledge, and try to connect this woman with Islamic websites that focus on inviting Christians, or with some knowledgeable sisters.