commit changes?

I have recently made SEVERAL changes to a database using PGAdmin III.
The database is tied to a website, and when I try to query the database,
my changes are not there.

I'm currently trying to get the support team to verify that my
datasource is actually pointing to the same database I am, but I
wondered about a couple of things:

1) I did all the changes as a user who was not the table owner, just one
with access to the tables. Could this be why the queries are coming
back without my columns?

2) I'm not aware of an equivalent option in PGAdmin III that performs a
'commit'. Is this necessary in order for my changes to go through? The
odd thing is that I've closed my database connection and reopened it, so
the changes are SOMEWHERE.

I tried searching your archive but none of the search terms I used came
back with any matching questions. I'm sorry if this turns out to be a
duplicate question. I'm not the best at coming up with search terms.