A couple of things to note.
1. Make sure your phone had mobile wifi hotspot. Go to Settings --> Wireless and network and look for the option.
2. Do you have unlimited data (or at least lots of data available)?
If the answer to both of those is yes you can create a portable hotspot. This uses your phone's data connection (3G) to create wifi access point that other devices can use. Just remember that everything you download use your phones data allowance.
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