Voices

Which part are you having trouble with - creating two staves, or putting two voices on a single staff? The Create New Score wizard should be more than happy to let you create two staves, and the Handbook section on Voices explains pretty clearly how to enter multiple voices.

using MuseScore 1.2

1. File -> New
2. Enter a title, Press next
3. On the instrument panel, choose voice and double click on tenor and bass. You will have score with two staves
4. Press Done
5. You have two staves one with treble clef, one if bass clef. I not, open the clef palette and drag the right clef to the right measure. See Clef
6. If you want to change the staff names, right click on it -> staff properties. Change the long and short instrument name. If you want to delete them, just select them in the score and press Del
7. You should be ready to enter the music. Since you want to have two voices per staff. Read carefully Voices