You will need two blank breaker spaces on the same side of the panel, one below the other. Then you will need to install a double pole breaker of the appropriate amperage rating in the two spaces. Purchase a sufficient footage of an appropriately sized cable with 2 conductors and a ground. Connect the two conductors to the double pole breaker and the ground to the ground buss. If you use NM-B cable (Romex or other brand) one conductor will be white and the other will be black. Tape the white conductor on both ends (on the insulation) with black electrical tape to identify it as a "hot".
This will give you 220 volts only. If you need a 110 volt control circuit as well, for a dryer or maybe a stove, you will need a three conductor with ground. Connect the two colored conductors to the breaker, the white conductor to the neutral buss (no need for tape), and the ground to the ground buss. The color to color voltage will be 220 volts, and either color to white will be 110 volts.
This will give you 220 volts only. If you need a 110 volt control circuit as well, for a dryer or maybe a stove, you will need a three conductor with ground. Connect the two colored conductors to the breaker, the white conductor to the neutral buss (no need for tape), and the ground to the ground buss. The color to color voltage will be 220 volts, and either color to white will be 110 volts.