Incandescent Wattage for 10g Tank?

I'm currently using a small heat dome for my almost 3-month-old Western Hoggy...

What heat bulb wattage is best for a 10G Terrarium? The tank is having trouble getting above 69°F - 71°F because it's January. Thanks! ☺

I would try a forty watt red bulb, if not a sixty should definitely do the trick. Hope this helps.

Depends on your room temperature.