You can learn thu'um words even if you dont have dragon souls.
However dragonsouls are needed to activate a shout word.
— Wikia - Elder Scrolls V: Skyrim - Word Wall
The player can choose to only vocalize part of a dragon shout which will lower the recharge time of the shout but cause the shout to be weaker. In an interview Todd Howard said every shout has 3 words and there is 1 word per word wall.
— Wikia - Elder Scrolls V: Skyrim - Dragon Shouts
FUS RO DAH: Force Balance Push (Unrelenting Force)
IIZ SLEN NUS: Ice Flesh Statue (Ice Form)
STRUN BAH QO: Storm Wrath Lightning (Storm Call)
YOL TOOR SHUL: Fire Inferno Sun (Fire Breath)
TIID KLO UL: Time Sand Eternity (Slow Time)
WULD NAH KEST: Whilwind, Fury, Tempest (Whilwind Sprint)
RAAN MIR TAH: Animal, Allegiance, Pack (Animal Allegiance)
SU GRAH DUN: Air, Battle, Grace (Elemental Fury)
FIN ZI GRON: Fade, Sprint, Blind (Become Ethereal)
FO KRAH DIIN: Frost Cold Freeze (Frost Breath)
ZUL MEY GUT: Voice Fool Far (Throw Voice)
ZUN HAAL VIIK: Weapon, Hand, Defeat (Disarm)
LOK VAR KOOR: Sky Spring Summer (Clear Skies)
HUN KAAR ZOOL: Hero Champion Legend (Call of Valor)
JOOR ZAH FRUL: Mortal Finite Temporary (Dragonrend)
KRII LUN AUS: Kill, Leech, Suffer (Marked for Death)
LAAS YA NIR: Life, Seek, Hunt (Aura Whisper)
OD AH VIING: Snow Hunter Wing (Call Dragon)
KAAN DREM OV: Kyne, Peace, Trust (Kyne's Peace)
FAAS RU MAAR: Fear Run Terror (Dismaying Shout)
SLEN TIID VO: Flesh, Time, Undo (Ressurect Dead Dragon, not available to player, Alduin)
N/A: N/A (Meteor Swarm, not available to player, Alduin)
FIIK, LO, SAH: Mirror, Deceive, Phantom (N/A, not available to player, Greybeards)
VEN, MUL, RIIK: Wind, Strong, Gale (N/A, not available to player, Alduin)
Best Answer
The three words of the Ice Form thu'um are as Iis, Slen, and Nus. They can be found in Frostmere Caverns, Mount Anthor (a dragon lair), and Saarthal.
You might already have one of the words from Saarthal, as the main quests seem to require you to visit the college at various points. Which typically means starting the mage guild quest-line that includes an expedition to the tomb early on.