I am installing electric baseboard heaters in 3 bedrooms and they are 240 volts and a have 3 slots in the panel to install the breakers. When I went to purchase them I was told that a single pole 20 amp breaker would work, however all that I have been reading is telling me that I need to install two pole because there is no neutral? But with a single pole breaker do you place both the black and the white (now hot wire) into the breaker and the ground to the ground bar? This is where the problem is. I was told that I can use a single rather than a double and unsure of how to connect it to the breaker and neutral bar.

I hate to sound cynical here, but these questions, and thoughts, tell me you really need to read up and get some experience before tackling this project.
I mean to not know the difference between a single pole and double pole breaker is a pretty significant thing.

Sure, knowing how to twist wires and make connections is all well and good, but you need to know what to connect to what, and WHY, so that you don't hurt someone or blow something up.

There are quite a few good books out there to gain at least the basic required knowledge on this.

Only a licensed Electricain should be working in your service panel... All 240 circuits require a two pole breaker in a residentail appliacion. I would disreguard any and all inforamtion from who ever told you a single pole breaker would work You must use a two pole breaker not two single poles as if one leg trips and the other does not you may have big problems. You also need to make sure your wire size is properly matched accordingly to the aperage of the breaker and appliance. A LICENSED Electricain would be your best bet.

B.

You have been lied to regarding this statement".... however all that I have been reading is telling me that I need to install two pole because there is no neutral?

You need dual pole breakers because both Hot phases create the 240 Volts you need.

For example, consider this, The Utility company delivers 240 Volts and up to 200 amps to your home.

This is called a "Single Phase". What happens next is that on the utility transformer the voltage is split. Neutral is centered between each phase to create two 120 Volt.

So if you measure from Neutral to either one of the legs you would see 120 volts. However, if you were to measure just between the two hot legs you would find 240 Volts.

Most branch circuits in a home are 120 volts circuits. That is why you find cables with just Black and White conductors along with a copper ground conductors.

On a speciality circuit like space heaters, Article 424 of the NEC covers space heaters, you would need 240 volts. Translated that means that just the two hot conductors are needed and neutral is not.

Also, because you need 240 Volts and this is derived voltage by adding the two phase together, you need one breaker each. They must be out of phase with each other and they must be a two pole breaker.

One other thought, Amperage. Because each baseboard heater is considered to be "continuous on". That translates to the amperage would need to be 1.25% higher, which means the Cale and the breaker may have to be re sized.

For example, if you heater needs 240 Volts at 30 amp, then:

30 X 1.25 = 37.5 (38) amps. That means you need to use #8 AWG and a 40 amp breaker.