You have an allocation of 100 Megabytes of disk space.  This is probably more than you need, but if you don't pay attention you may find that you can't create any new files or save ones that you have changed.

To check your quota type
quota -v
and you will get output such as:

Disk quotas for joe_user (uid 1000):
Filesystem    usage   quota   limit    timeleft  files   quota   limit    timeleft
/home         65976  100000  250000               3098       0       0

This tells you that you are using 65.976 Mb (the numbers are in kilobytes, so divide by 1000 to get Mb)

You are allowed to have more than 100 Mb for one week in case you need to use some big files for a few days- in our case you can have up to 250Mb, but only for one week.  After 1 week, you can not write any files!

If you see something like:
Disk quotas for joe_user  (uid 1000):
Filesystem    usage   quota   limit    timeleft  files   quota   limit    timeleft
/home        136136  100000  250000    3.0 days   2670       0       0

This tells you that you are using 136Mb, and only have 3 days left to get back down to 100 Mb.

If you need to write some really big files, you can use the /scratch directory, e.g. save file to /scratch/junk.dat
Note that /scratch files can be deleted at any time, so don't save critical things there!!!