The next screen will says you have created your zip file. Click on finish button. Then exit to close the program. Highlight the file you want to unzip, see selecting a file above. Then click on the next button.
Some zip files contain more than one file.
At the select files screen you can select only the files you want to unzip. After you have selected the files you want to unzip click on the next button. The next screen asks you to select the destination folder you want to save the files to. After you have selected a location click on next. The next screen will says you have unzipped your files.