Legolas, if you break it's meaning down, 
means "Greenleaf". Legolas is Prince
of Northern Mirkwood.  His father is
Thranduil, Elven King.  Thranduil was
the king that locked away the dwarves
on their quest through Mirkwood for 
their stubbornness.  Thranduil sent 
Legolas to Rivendell bearing a message
to Elrond, and he was summoned to the
secret council meeting.  When they 
decided to destroy the ring, Legolas
was chosen to accompany Frodo to however
far he was willing to go.  They then set
out on their journey.  In Moria, he
recognized the legend of the Balrog,
which is one of the main reasons Elves
and Dwarves dont get along.  When Moria
was built, Elves were still friendly.
However, when the dwarves delved too
deep into the mountain, they released
an ancient and fearsome creature made
of shadow and flame, the Balrog.  When
they lose Gandalf, the party goes to
Lothlorien.  When Gimli sees the Lady 
Galadriel, he is enchanted, and has no
more harsh words against the lady -- in 
fact, he dare not speak it!  It is around
this time when Legolas and Gimli build
their friendship.  The party departs 
from Lothlorien, then they come to the
point where the ringbearer must decide
where they will go.  However, when they
are overrun by orcs, they have their hands
full.  The orcs take Merry and Pippin 
hostage, and Frodo and Sam have already
left.  They decide to follow the orcs,
and go after Merry and Pippin.  They follow
their trail to Rohan, where they meet Eomer.
Eomer speaks harsh words to Gimli, and 
Legolas replies with threatening his life,
for saying such things of his dwarf friend.
Aragorn, that smooth talker, breaks it up.
They follow the tracks into Fangorn, and 
Legolas is facinated by the trees of the 
Forest, and how old they are.  That is when
they meet Gandalf, and are told that the 
hobbits they've been tracking are safe and
sound, and that their help is needed elsewhere.
They go to Theoden, and once his trance is 
broken, they head for Helm's Deep.  During
the battle, Gimli and Legolas begin a contest
of who can kill the most orcs.  Afterwards,
they go to Minis Tirith, and then Legolas 
follows Aragorn into the Paths of the Dead.
The come back by the end on black ships, as
to fool their enemies.  Then after much discussion,
they march to the Black Gate to form as a possible
distraction for Frodo.  Just as all hope seems
to be lost, Mordor falls apart, as the ring
has been destroyed.  Legolas and Gimli made a
promise to one another that after the war, Gimli
would go with Legolas to the forests, and Legolas
would go to the caves with Gimli.  They withheld
that promise, and when Aragorn died in 120 FO,
Legolas built a ship, and took Gimli with him,
to reunite with his people.