A simpler way might be:
cp .bashrc .bashrcbackup
echo "alias rm='rm -i'" >> .bashrc
Note the placement of the period --the filename is not "bashrc" but ".bashrc", and also note the spaces and which quotes are double and which are single. The above command copies your ".bashrc" file into a backup, and then adds the line
onto the end of your ".bashrc" file without needing an editor. This way, every time you type the "rm" command (to delete files), you're really typing "rm -i", which will ask you whether you are sure.
The command "rm -rf /*" mentioned above will delete every single file on your drive, and is only recommended for masochistic nerds who have nothing better to do.