1. If you use an iPhone, go to Home>Settings>Personal Hotspot and tap the icon to "On" / Green. This will show the WiFi password.
2. On the iPad go to Home>Settings>WiFi tap the icon to "On" / Green. Select the network with your iPhone's name and enter the pass word from step 1
To use a SIM card in the iPad it must have a SIM-card slot, not all iPads do. Can you connect to free public WiFi spots with the iPad or with the phone? If you can, the job is oxo with nothing else to do.