Q: If I buy a 4s iphone Can I use it to connect my imac ox's 10.4.11 to the internet If so how through bluetooth airport ect.

Take a look here:

http://support.apple.com/kb/HT4517

Regards.

Yes you can, some carriers like verizon charge for the servie though. But you can do it over bluetooth, wifi and cord, if you really want to. I do it all the time with my Ipad. hHope that helped

You have to have hotspot service added to your phone plan.  However, if you are using either Verizon or ATT, they have new plans just announced (Verizon has it up and running) that include free hotspot capabilities along with shared data if multiple smartphones are used on the account.