Your cover is in poor condition and the stamp is poorly centered. If the cover and the stamp were in better condition you might get lucky and be able to sell it on eBay
for around $1, but in this condition you might struggle to get 50 cents. Then you have to pay the eBay
insertion and final sales price fees and so your final amount in your pocket might be in the range of 10 cents to 25 cents. This assumes that you do not place any value on your time to put it up for an eBay
auction. If you did think that your time has any value at all and you pay yourself a minimum hourly wage for your time and effort to auction it, then you would likely end up with a net loss in selling it. On the other hand, if you want to collect this kind of cover then you should put it in your collection and enjoy looking at it from time to time.