If you like to use your 3.8GB DVD as your local Repo which you dont need to download for any further application install, you can use the option <Add custom medium> in the Software Manager.
but when I tried this, I had an issue that I cannot find the DVD medium. After some searching, I found it here
/run/media/username/Mageia-2-i586/
add this in your DVD location and use it as your main Repo..
wishes..