Vanessa, 39, admits that it does not immediately come to grips with the instrument, but Johnny, 48, was never angry with her.
"Johnny is a good teacher. He has enormous patience, which was necessary when I learned to play guitar," says Vanessa.
"He not only bought me a beautiful guitar, he showed me how to bring music out of it.
"He must be patient because I am slow learner".
Vanessa - who was forced to deny rumors that she and Johnny had split earlier this year - was the actor for 14 years and the couple has two children, daughter Lily-Rose and son Jack.
The Golden Gods Awards in Los Angeles last month, Johnny played guitar on stage with rock musician Marilyn Manson - but Vanessa admits she is not quite the same level as her partner yet.
"Frankly, my guitar is really pathetic. I do not practice enough," says Vanessa Live.
"But I love the instrument. When you own a guitar, you are never alone."
