The antenna you described is not a long wire - a true longwire is one or more wavelengths long at some frequency and usually close to the ground.
What you have there is an untuned dipole (without knowing lengths it would be difficult to work out what frequencies it would be resonant on...). You have a couple of choices here; cut the wires so they are resonant on a band you wish to concentrate on (and it would then work on odd harmonics of that band - for example a 4 mhz dipole would also be resonant on its 3rd harmonic, or 12 mhz). The classic 234/f(mhz) would give you the length for each leg in feet, where f(mhz) is the frequency in mhz.
The other, and much more flexible choice, is to feed the 2 wires separately, bring them each down to a 9:1 transformer (one for each antenna) which itself is grounded, then ground the coax for lightning protection purposes via a lightning arrestor. You didn't say what radio you are using this with, but if it's one of the better desktops, SDRs, etc. that too should be grounded. As long as they're far enough part, likely they won't interact with one another, and sometimes what is not well heard on one antenna might be better on another. Propagation can be funny about that sometimes.
You can construct these 9:1 transformers yourself, or buy them. There are a couple of links to these in our HF antennas wiki - Grove Enterprises sells the WinRadio MLB, and there are others...(note all links are in blue)
HF Antennas - The RadioReference Wiki
A good earth ground is often NOT just a single copper rod rammed into the ground; there are specific electrical codes that address proper grounding techniques (you would need to see what these are in your area), and this has been discussed in great detail in this forum. You can use the search tools to find out about this.
73 Mike
