when i install new wallet it's has one address already.when i click new Address it generates 2nd Address and So on
is Wallet Connect Viva API for creating new address?How it works?
After installing a wallet it will generate a random(!) seed. This seed will be used in 'mathematical equations' to derive your private keys.
These private keys 'allow you to spend from the corresponding address'.
There is no API necessary. Each client creates private-/public keypairs itself. There is no central authority in a decentralized system.
Q3 same other functionalities balance checking etc..
Depending on what language you want to use, there are quite a few libaries available which make it plain simple for you to create priv-/pub keypairs, send/receive transactions, etc...
The best way would be to google it yourself: 'bitcoin + libary + YOUR_PROG_LANGUAGE'