I want to alphabetize one of the columns in a spreadsheet

how do I alphabetize one column and still keep the accompanying columns?

“keep” means that they should not be changed at all? An example would help. See guidelines for asking.

You have to select all the columns that belong together, then select Data - Sort, in the dialog window you then select what column to sort by, you can select a second and third column as well, then the rows will be sorted by those criteria.

Say we have this data.

a	a	a
b	b	b
c	c	c
d	d	d
e	e	e

To produce this result:

a	e	a
b	d	b
c	c	c
d	b	d
e	a	e

…select column B, go to Data → Sort and choose Current Selection. Then specify to sort Descending.

sort range

If, however, you want this result instead:

e	e	e
d	d	d
c	c	c
b	b	b
a	a	a

…then select all three columns, as described in @floris_v’s answer.