What is the proceedure for one who missed davening on Rosh Chodesh morning? I know he can make up shacharit with tashlumin at mincha, but what about Hallel and Mussaf? Can he make those up as well? And if so, what is the order of everything he must say? Todah rabbah

Shalom, Yes, if you unfortunately missed davening on Rosh Chodesh, you must make up Shacharit with an extra Amidah at Mincha. Hallel may (and must) be recited even in the afternoon, as must Musaf. The other prayers are "made-up for" as on any day you miss Shacharit - that is the morning blessings may be said all day. Shema must be recited (all three paragraphs), but the blessings before and after Shema may not be said, and neither may the blessings of Baruch She'amar and Yishtabach be recited.All the other parts of the service may be recited all day long. If it is already afternoon, one should first say the morning blessings. The rule is that even though we usually pray Musaf before Mincha, if it is already Mincha time, then one should say Mincha before Musaf. So pray Mincha, saying the Amidah twice to make up for the lost Shacharit, then Hallel and finally Musaf. Blessings.