I have two lines, one with two bare wires red and black, the other line has a red a black a white and a ground wire. How do I hook them together? I know I'm not supposed to put a neutral with a ground wire; what do I do with the neutral wire?
What you have in these pictures is a massive code violation, fire hazard as well as an electrocution hazard. This must be rectified first. Leaving this mess intact is negligent even if you cover it with a mile of electrical tape.
You need to put all of this cable into a listed electrical box. Since we cant see the conductor size, I'm just going to recommend a pull box, something around 6x6x3 inches to make life easy. Each cable must have at least 6 inches of jacket/sheath removed and the individual conductors must be able to extend 3 inches form the front of the box. So 6 inches is plenty. The cables must also be held securely to the box with proper cable clamps. Buy properly sized wire nuts or listed splicing device to make the connections between conductors. The ground conductors must also be securely bonded to the junction box as well. Multiple individual wire nuts designed for smaller conductors is begging for trouble. The cost of these materials is negligible compared to a fire.
Until then, I am not going to help you any further and neither should anyone else.
Could this be a multi wire branch circuit? If it is or not the connections need to be made in an accessible box. A box that when everything is done can be accessed. If the voltage on the red and black voltage is 240 but the voltage from red and or black is 120 this could be the case. We need more information to really help but other than no box for the connections it could be totally safe and legal by the latest code revision in 2014. Looking at this on my phone I could not tell that the wires were split and wire nutted together with 2 wire nuts on 1 wire. Now that I see this and the heater comment realize it is a simple 240v circuit that has been assembled in a way that is downright dangerous. An accessible box is still needed and the proper size wire nuts or crimp connectors if you can provide the wire size we can give you the required box size. The box can be metallic or non metallic.