I'm tying to change the number I have on an attribute in a script, but I don't know how to!
Any help would be appreciated!!

Hello.

Have you completed the tutorial? It is fairly short, and it teaches us how to do that and all sorts of other nifty stuff.

http://docs.textadventures.co.uk/quest/tutorial/creating_a_simple_game.html

To actually specifically help you:

http://docs.textadventures.co.uk/quest/using_attributes.html

(filler for getting my edited post, updated/posted)

creating an Attribute and setting its initial Value:

add new script -> 'variables' section/category -> 'set a variable or attribute' Script -> (see below)

set variable NAME_OF_OBJECT.NAME_OF_ATTRIBUTE = [EXPRESSION] VALUE_OR_EXPRESSION

for some examples:

set variable player.alias = [EXPRESSION] "HK"
set variable game.introduction = [EXPRESSION] "Hi, welcome to my game, I hope you enjoy it!"
set variable game.state = [EXPRESSION] 0
set variable player.strength = [EXPRESSION] 100
set variable orc.dead = [EXPRESSION] false
set variable player.flying = [EXPRESSION] false

Directly Changing an Attribute's Value:

add new script -> 'variables' section/category -> 'set a variable or attribute' Script -> (see below)

set variable NAME_OF_OBJECT.NAME_OF_ATTRIBUTE = [EXPRESSION] VALUE_OR_EXPRESSION

for some examples:

set variable player.alias = [EXPRESSION] "John Doe"
set variable game.introduction = [EXPRESSION] "In this game of mine, if you die, you die in real life, muwhahaha!"
set variable game.state = [EXPRESSION] 75
set variable player.strength = [EXPRESSION] 25
set variable orc.dead = [EXPRESSION] true
set variable player.flying = [EXPRESSION] true

Arithmetic'ally (Addition, Subtraction, Multiplication, Division, and Modulus) Changing an amount (Integer/Double) Attribute's Value:

Arithmetic Operator Symbols:

Addition: +
Subtraction: -
Multiplication: *
Division: /
Modulus (division, but it gets/finds/returns the REMAINDER): %

add new script -> 'variables' section/category -> 'set a variable or attribute' Script -> (see below)

set variable NAME_OF_OBJECT.NAME_OF_ATTRIBUTE = [EXPRESSION] VALUE_OR_EXPRESSION

for some examples:

set variable player.strength = player.strength + 5

set variable player.maximum_life = [EXPRESSION] (player.strength + player.endurance) / 2

// doing it directly in code-scripting, is slightly different (shorter, lol) than doing it via the GUI/Editor's 'add new script':
// create ("katana")
// katana.damage = 50 // set variable katana.damage = [EXPRESSION] 50
// player.weapon = katana // set variable player.weapon = [EXPRESSION] katana
// player.strength = 100 // set variable player.strength = [EXPRESSION] 100
set variable player.damage = [EXPRESSION] player.weapon.damage + player.weapon.damage * player.strength / 100
// player.damage = [50] + [50] * [100] / 100 = 100

// player.strength = 0 // set variable player.strength = [EXPRESSION] 0
set variable player.damage = [EXPRESSION] player.weapon.damage + player.weapon.damage * player.strength / 100
// player.damage = [50] + [50] * [0] / 100 = 50

// player.strength = 50 // set variable player.strength = [EXPRESSION] 50
set variable player.damage = [EXPRESSION] player.weapon.damage + player.weapon.damage * player.strength / 100
// player.damage = [50] + [50] * [50] / 100 = 75

// player.strength = 75 // set variable player.strength = [EXPRESSION] 75
set variable player.damage = [EXPRESSION] player.weapon.damage + player.weapon.damage * player.strength / 100
// player.damage = [50] + [50] * [75] / 100 = ~ 87

// player.strength = 25 // set variable player.strength = [EXPRESSION] 25
set variable player.damage = [EXPRESSION] player.weapon.damage + player.weapon.damage * player.strength / 100
// player.damage = [50] + [50] * [25] / 100 = ~ 63

Concatenation'ally Changing a String Attribute's Value:

Concatenation Operator symbol: +

an example:

set variable npc.greeting = [EXPRESSION] "Hi"
// msg (npc.greeting)
set variable npc.greeting = [EXPRESSION] npc.greeting + ", my name is HK."
// msg (npc.greeting)
set variable npc.greeting = [EXPRESSION] npc.greeting + " What is your name?"
// msg (npc.greeting)

// output/display/results:

Hi
Hi, my name is HK.
Hi, my name is HK. What is your name?