As long as you have 7Zip installed, the rest is usually automatic. To send a zipped file, right-click on the file and then click on Send to. Then in the list click on Compressed (zipped) Folder, at this stage nothing appears to happen, but if you look in your My Pictures folder you will see a Zipped file, usually it is the last file in your My Pictures. You can then create a email and add that compressed file from your My Pictures to the email as a Attachment, then Send in the normal way.
LG G6 review: Hands-on with LG’s bold, big-screen shot at perfection