Making iso in ubuntu is fairy easily task to do, here is how i did it.

* Open brasero
* Choose Data project
* Find your files and just press the Add (plus button at the top left corner)
note: you cannot drag and drop
* Then select Burn

If you insert a cd/dvd it will as you for either burning it to your cd/dvd or to an Image File, choose the Image File
If you didn’t insert a cd/dvd, then there is only one option and that is the Image File

* Click burn and it would be at your home folder (Alt+F2 then nautilus)

Then you can save or distribute your iso files.