DW will not see 'all' fonts you've installed on your computer.
DW will only (by default) work with system standard fonts.
If you want to use a 'custom' font, you have to define a 'web-font' within DW.
Once you do this, you should also upload the fonts on your server as a 'web-font' for your remote visitors to be able to see the font. Remember, not all users will have the 'custom' font you're using on your webpage - meaning you have to provide the webfont on your server so the browser will render the font from the server and display it to the end-user.
Note: Be sure you're not violating the font licenses. Not all fonts can be used on the web. Not all of them are free to use. My sincere recommendation is for you to use one of the open-source webfonts from google fonts api. In this case, you don't have to embed anything into your server. You can just point to the desired font on Google fonts in your <head> tag and they will be fetched from Google during rendering.
From the Win/Mac Web Safe font list to embedding Custom Web Fonts in your web pages: