Help me I need help

I have one friend she is my friend about 4 years become we are friends too close friends and she sent the letter and she said to I don't need visa I can come to Brazil only with that letter to she sent for me and I don't need interview or another periods I don't know what I do because in Afghanistan doesn't have Brazil embassy I am so confused please help me.

https://sistemas.mre.gov.br/kitweb/data … Brazil.pdf

This suggests you do need a visa.
It's highly unlikely a country Brazil has no diplomatic relationship with will get visa free travel.

The rest is contacting either Brazilian immigration via their website or perhaps a visa agent but the latter could leave you open to scammers so make sure you know the requirements and costs before you contact them.