if you leave the fermentation open to the air without some kind of valve to keep new oxygen out and let the co2 created by the fermentation get out, you will cause the yeast to make vinegars, which will make it taste like, well, vinegar. Also, without a distillation, the mixture you fermeted will only be able to get 8 to 20 percent alcohol, depending on what type of yeast you use, given optimal conditions. 8% would be regular bread yeast and 20% would be special so-called "super-yeasts" sold specifically for making neutral spirits for distillation, for the purpose of making fuel alcohol. You can however drink it, it just usually has a high concentration of fussel oils and byproducts that affect taste and cause hangovers.

maybe i'll post the way I make a really easy homemade wine in a little bit.