You make Tests by making a percentile roll and comparing the result to a Target Number, often referred to as TN, and typically a value between 1 and 100. If the roll is less than or equal to the target number, the character succeeds. If the roll is higher than the target number, they fail.
Example
A character is attempting a very difficult task at which they are relatively skilled. After accounting for modifiers, they deter- mine that their target number for the test is 37. They manage to roll a 32, below their target number, so they succeed!