You can't. A transaction must be broadcast to the network via the internet in order to be verified and then mined in to a block.

That does not mean, however, that each individual needs internet access. You simply need some way of getting a transaction on to the internet. Each person can easily sign transactions on their offline devices, and then save those transactions as a small text file. All you need then is some way of getting those small text files to a person/node/service who will broadcast them for you. If you have a public WiFi spot in your community, then you can travel there and use that. If one person has a mobile device or similar with internet access, they could potentially set up a service broadcasting transactions on behalf of other people. There are services which allow you to send transactions via SMS as pointed out above. You could even transmit a transaction via phone call or radio to someone with an internet connection who could broadcast it on your behalf.

Since you are posting on this forum, you must have internet access somehow. Could you set up a method using whatever connection you are on now to broadcast transaction on behalf of your community?