Not to worry - it's not at all complicated!
In computer language, a 'zip' file has been compressed. That means a technique has been applied to make the file occupy less space on your hard drive while remaining the same in every other way. In effect, the file has gone on a diet.
Attaching a zip file to an email message is the same as attaching any other type of file. Every email program is a little different, but they all have a symbol somewhere that looks like a paper clip. (A younger person never heard of a paper clip.) Just click on that paper clip and a window will open that allows you to search for the file you want to attach.
When you've found the zipped file, either double-click on it or click once and select Open. When you do that, a copy of the file will attach itself to your email. It usually takes a few seconds for this to happen.
If a compressed file is 'zipped' what do you call it when it's uncompressed? Why, 'unzipped' of course! 😉