All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
Anal intercourse is totally forbidden. So, Muslim spouses must not practise it under any claim. As your wife is a new Muslim, you can gratify her with any other lawful method.
Ibn Thabit (may Allah be pleased with him) said, “The Messenger of Allah (blessings and peace be upon him) said, “Allah is not too shy to tell the truth.” three times. “Do not have intercourse with women in their back passages.” (Narrated by Ibn Majah and authenticated by al-Albani)
This only applies to anal intercourse, which is the introduction of the male’s genital organ into the anus. Since she is a new Muslim, you may try to gratify her needs in whichever way other than the forbidden anal intercourse.