My aunt wants to install a 220 electri heater and want sto know how to do so.

Call an electricain. They will be able to get the heater, and wire it correctly from breaker box to heater.

If you feel qualified to install it yourself, you will need to just buy the heater(im assuming baseboard) and wire it using correct size wires and hook it to the breaker box to a dedicated 240 breaker. Honestly, it would be best to have an electrician come and hook up the power source. You should have no problem mounting the electric unit yourself, but would seriously recommend having a pro take care of wiring. Let me know what you decide.