[INST] how do i address an envelope? [/INST]Do you mean how do you address a letter, or an envelope in general?</s>[INST] i want to send a letter, with an envelope [/INST]
Here is the appropriate format to use when addressing an envelope to send a letter:

Recipient's Full Name
Their Street Address
City, State, Postal Code
Country if applicable
OK, I’m not sure about the first part of that, but for the second part, this website shows how to address an envelope.  If you don’t know what the proper way to address a letter is, check here for an explanation of US address formats.