Before we get into the spell list for The Warlock, lets begin with a brief refresher on what it means to cast spells as a Warlock, as well as how to prepare and cast spells as a Warlock:
Your research into the Wyrd and Arcane, as well as the magic bestowed on you by your patron have given you facility with spells.
At 1st level, you know two Warlock Cantrips of your choice from the Warlock spell list. You learn additional Warlock Warlock Cantrips of your choice at higher levels, as shown in the Cantrips Known column of The Warlock table.
The Warlock table shows how many spell slots you have to cast your Warlock spells of 1st through 5th level. The table also shows what the level of those slots is; all of your spell slots are the same level. To cast one of your Warlock spells of 1st level or higher, you must expend a spell slot. You regain all expended spell slots when you finish a Short or Long Rest.
For example, when you are 5th level, you have two 3rd-level spell slots. To cast the 1st-level spell Witch Bolt, you must spend one of those slots, and you cast it as a 3rd-level spell.
At 1st level, you know two 1st-level spells of your choice from the Warlock spell list.
The Spells Known column of The Warlock table shows when you learn more Warlock spells of your choice of 1st level or higher. A spell you choose must be of a level no higher than what's shown in the table's Slot Level column for your level. When you reach 6th level, for example, you learn a new Warlock spell, which can be 1st, 2nd, or 3rd level.
Additionally, when you gain a level in this class, you can choose one of the Warlock spells you know and replace it with another spell from the Warlock spell list, which also must be of a level for which you have spell slots.
At 11th level, your Patron bestows upon you a magical secret called an Arcanum. Choose one 6th-level spell from the Warlock spell list as this Arcanum. You can cast your arcanum spell once without expending a spell slot. You must finish a Long Rest before you can do so again.
At higher levels, you gain more Warlock spells of your choice that can be cast in this way: one 7th-level spell at 13th level, one 8th-level spell at 15th level, and one 9th-level spell at 17th level. You regain all uses of your Mystic Arcanum when you finish a Long Rest.
Charisma is your spellcasting ability for your Warlock spells, so you use your Charisma whenever a spell refers to your spellcasting ability. In addition, you use your Charisma modifier when setting the saving throw DC for a Warlock spell you cast and when making an attack roll with one.
Spell save DC = 8 + your proficiency bonus + your Charisma modifier
Spell attack modifier = your proficiency bonus + your Charisma modifier
You can use an Arcane Focus as a spellcasting focus for your Warlock spells.