When you log into a Unix machine, whether remotely or on the console, an interactive shell is run. Many shells exist with different features (bash, tcsh, zsh36, or other shells37). When your account is created your default shell is set (probably as bash or zsh -- there is currently a debate about which).
At the time of login the shell runs your startup scripts. These specify aliases, run useful programs and display information to your terminal. For zsh the startup script is .zshrc. Be very careful editing this script -- change it incorrectly and you may be unable to log on to some or all machines.
To avoid this happening, test the script before logging out. The command 'source ~/.zshrc' should do the trick. This will run the script and (hopefully) report any errors. Alternatively re-run your default shell (by entering the relevant command like 'zsh -l' or 'bash'). The new shell will load the global configuration and your local configuration in the normal order. Press CTRL-D to return to your previous shell prompt once you have noted any errors.
An important point needs to be made here. Your path is the list of directories scanned by your shell when you attempt to run a program. You may often wish to run programs in the current directory.
By default the UCC login scripts do not include the current directory (also referred to as the '.' directory) in your path. You need to explicitly state the location of the program you wish to run if it is in the current directory, and that directory is not in your path. If you have a program 'hello' in the current directory, you would type './hello' to run it.
If you wish you may add the current directory to your path. It is not there default for an important reason -- the current directory may contain hostile executable files. For example, if a hostile program named 'ls' was in the current directory you might type 'ls' and suddenly have all of your files deleted.