  Fix an odd prime $p$. Let $G$ be a compact $p$-adic Lie group containing a
closed, normal, pro-$p$ subgroup $H$ which is abelian and such that $G/H$ is
isomorphic to the additive group of $p$-adic integers $\mathbbZ_p$ . First we
assume that $H$ is finite and compute the Whitehead group of the Iwasawa
algebra, $\Lambda(G)$, of $G$. We also prove some results about certain
localisation of $\Lambda(G)$ needed in Iwasawa theory. Let $F$ be a totally
real number field and let $F_{\infty}$ be an admissible $p$-adic Lie extension
of $F$ with Galois group $G$. The computation of the Whitehead groups are used
to show that the Main Conjecture for the extension $F_{\infty}/F$ can be
deduced from certain congruences between abelian $p$-adic zeta functions of
Delige and Ribet. We prove these congruences with certain assumptions on $G$.
This gives a proof of the Main Conjecture in many interesting cases such as
$\mathbb{Z}_p\rtimes
