A good video tutorial of basic functions for an abacus have been published on youtube by Lindblå Läs och Skrivutveckling. This is a good starting point for anybody wanting to learn how to use an Abacus to improve their arithmetic skills.
More interesting tutorials in the published series:
The exchange method up to 5
Complementary numbers up to 5
The exchange method up to 10
Complementary numbers up to 10
Complementary numbers above 10
Difficult positions on the modern Abacus