Alternatively, if you want to use the command line and you're just interested in which files are taking up the most space, I often use the find command.

find ~ -size +50M

will find all files within your home directory (~) greater than 50MB.

You can modify the size descriptor after the number like so (see man find)

k       kilobytes (1024 bytes)
M       megabytes (1024 kilobytes)
G       gigabytes (1024 megabytes)
T       terabytes (1024 gigabytes)
P       petabytes (1024 terabytes)

Alternatively, if you want to use the command line and (looking at the 2nd part of your question) you're just interested in which files are taking up the most space, I often use the find command.

find ~ -size +50M

will find all files within your home directory (~) greater than 50MB.

You can modify the size descriptor after the number like so (see man find)

k       kilobytes (1024 bytes)
M       megabytes (1024 kilobytes)
G       gigabytes (1024 megabytes)
T       terabytes (1024 gigabytes)
P       petabytes (1024 terabytes)