How do I unlock my iPhone 5s - Nokia 6500 Slide Cellular Phone

take it to a service shop and have it done

Better pay little 10 to local experts they unlock it for you withing minutes :)

Try this site:
http://sim-unlock.net/unlock/Iphone/

All supported modeles for Unlock by code Iphone sim unlock net

This website claims the iPhone 5s ships unlocked.

The Verizon iPhone 5s comes unlocked just like the Verizon iPhone 5

The Touch ID feature in the Apple iPhone 5S detects the iPhone owner's fingerprint and uses it kind of as a password, unlocking the phone and allowing purchases.
The more the feature is used the better the phone detects the fingerprint. The system can detect the fingerprint from different angles and rotations.

In the US the iphone 5s is compatible with AT&T, sprint, t-mobile and verizon. You can order it from Apple unlocked to work on other networks if you wish.