A good way to start is to download templates from the Microsoft website. They will allow you to modify their templates according to your preferences, but they'll also offer an easy way to make your own. Using Microsoft Word, you can make your own label templates, quick and easy. If you look at the top and on the edge, you'll see some measurements. Those measurements will help you gauge the location of the label parts. Move them around and try them out, change fonts or locations, add pictures and so on, and once the label looks like you want it, click File, Save As and select Word Template. Under File Name you can give it the name you want. Click Save to save your modifications. It's as simple as that. You can create as many templates as you want, and all of them will be stored in Open Office documents.
Click on the the template. At the bottom right of the dialogue you'll see two options: 'Document' and 'Template'. If you want to use the letterhead to send as a document or letter, choose 'Document.' If you want to edit the template, choose 'Template.' When you choose 'Document,' it gets saved as an MS Word document.