Prologue to the Codex Hammurabi,
details on the first few lines

The structure of the prologue is basically one main sentence, with many subordinate clauses. The verb in Akkadian comes at the end and the verb of the main sentence appears in tablet V line 23. The dependent clauses in between are often epithets describing the deeds of the gods and the good works of Hammurabi. Without the dependent clauses the prologue is simple:
'I, Hammurabi, established:' (followed by the actual codes)
With the notation for tablets and line numbers, the structure of the first introducing clause is

• I.1 When (the gods Anum and Enlil) .....,
  I.27 when (they elected) me, Hammurabi, ......,
  I.49 they elected;
  I.50 I, Hammurabi, ........,
  V.23 I established
  V.24 and I let the people prosper
  V.25 Then:
  

Explanation of the first few lines

I.1
	ì-nu	AN	sci-ru-um
	inu	Anum	Scïrum
	When	Anum,	the sublime,

Anum, Sumerian AN, is the supreme god, god of heaven;
inu is the temporal conjunction 'when'; later (as in the Enüma eliš epic) it is enüma or inüma;
Sc here stands for tsade, the emphatic s, usually written with a dot under the s;
I use ï, ä, ü to indicate long vowels for lack of anything better within the html-limitations. They are usually written with a macron on top of the vowel;
AN has more meanings but is here logogram for the god Anum, which is in this case the same word as the Sumerian name AN plus the usual Akkadian ending -um is added (-um is the 'default case' and also masc. nominative singular).

I.2
	LUGAL	d.	A-nun-na-ki
	šar		Anunnaki
	'King of the Anunnaki'

Anunnaki, a Sumerian loan word, is here the collective name for all the gods. The word carries the determinative d for deities. It is used sometimes interchangeably with 'Igigi'. In other texts the gods are divided into gods of heaven ('Igigi') and gods of the underworld ('Anunnaki').
šar (where š denotes the letter shin as in shashlick) is the so called construct state of the noun šarrum 'king'. The construct state is used when the noun is followed by a noun in the genitive or by a possessive pronoun. (Anunnaki is a virtual genitive: you can't see it from the form (case endings) because proper names are often not declined), e.g.

• 'Landlord' would in Akkadian be written as 'lord land', with 'lord' in the construct state and 'land' in the genitive.
  šar šarrï (with long i, here written as ï, the genitive masc.plural)
  'king of the kings'
  

I.2 I.3+4+5
	d.	En-líl	be-el	ša-me-e	ù	er-Sce-tim
	d.	Enlíl	bël	šamê	u	erScetim
		'(and) Enlil,	lord of	heaven	and	earth'

bël is the construct state of bëlum 'lord' and is followed by the genitive of šamû 'heaven', 'sky' and erscetum 'earth'.
The word for 'heaven' is a contraction from šamä'ü with two long vowels and an aleph in between. It is plural. Contracted vowels are transcribed with circonflex, like in many languages. They are pronounced as a long vowel as compensation for the lost consonant. E.g. French hôpital (long o, < hospital with lost s).
u is a word by itself 'and'. It is here written as u3, but one could also encounter

• u2, or
  u (rarely)
  

• AN 'heaven' and KI 'earth',

Enlil is the sky-god. The gods Anum and Enlil are both supreme gods, king of heaven and earth. In tables of deities they are listed first in hierarchy, followed by the mother goddess and three astral gods Sin (Moon), Shamash (Sun) and the goddess Ishtar (Venus).
In pictures Anum and Enlil carry 10 pair of horns, the same emblem for both of them: in the world of the gods Kingship is shared. In some texts (like this one here) there appears a division of tasks, where Anum is King of the gods and Enlil is Lord of heaven and earth. In mythology Anum is a somewhat dim personality, whereas Enlil has a definite character, central in many epics.

I.6+7
	ša-i-im	ši-ma-at	KALAM
	šä'im	šimät	mätim
	who decreed	the fates of	the land

šä'im is the (active) participle of the verb with infinitive šiämum or šâmum 'to decree'; the participle normally functions as a noun and indicates 'the person who...', 'he who ...'. It is here in the construct state (nominative ending -um falling off), because it is followed by a combination of construct state plus genitive.
šimät is the construct state of the fem. plural form šimätum of šimtum 'fate'.
KALAM is logogram for mätum 'land', here as a genitive 'of the land'.

An important task of the supreme god Enlil is to decree the fates of mankind (kings, ordinary people, countries etc.). The fates have been determined in the assembly of the gods, presided by Enlil.