My husband is interested in Islam-how can I support him?

Assalamu alaikum, everyone. I need some advice. My husband (42) served multiple deployments in the Middle East as a medic. During his time there, he developed a deep love and respect for the Muslim people and felt a strong pull toward Islam. He truly believes in his heart that he is Muslim. Now he wants to visit a mosque and officially embrace Islam-is it “shahada” that he needs to say? He comes from a Hispanic background and was raised Catholic, but he feels genuinely called to Islam. I’m not religious myself, so I’m unsure how to best support him. What should be his first steps? Jazakum Allahu khair for any guidance.