collinsmi
I suggest the following 3 things...
attend a few Open NA meetings together.
Get your sponsee a copy of the Narcotics Anonymous Basic Text for him to read
Read the pamphlet on NA 'Sponsorship'
http://www.na.org/pdf/litfiles/us_english/IP/EN3111.pdf
Read the pamphlet
'Am I An Addict'
http://www.na.org/pdf/litfiles/us_english/IP/EN3107.pdf
Read the pamphlet 'For the newcomer"
http://www.na.org/pdf/litfiles/us_english/IP/EN3116.pdf
Read the pamphlet 'Welcome to Narcotics Anonymous'
http://www.na.org/pdf/litfiles/us_english/IP/EN3122.pdf
Read the pamphlet 'Who, What, How, and Why'
http://www.na.org/pdf/litfiles/us_english/IP/EN3101.pdf
armed with these experiences, I think he will come to a decision that will sit well with him.