Examples:

• But that's only because I don't know how to use it yet.
• But, I don't know how to use it.
• Yes, I've learned it but I don't know how to use it.
• I don't know how to use it.
• However, I don't know how to use it.
• Yes! I don't know how to use it very well, so don't make any sudden moves!
• I can't find the companion to my new coffee maker, and I don't know how to use it!