Raven, only 4 ingredients are ABSOLUTELY necessary for baking:
- Flour (You want something with about 12-14% protein for good gluten development)
- Salt (This regulates the yeast development, softens gluten, and provides some flavour
- Water (This provides a good environment for the yeast, and should not be too hot or too cold)
- Yeast (Active Dry is crap, make sure to buy Instant Dried Yeast)
Any additional ingredients will increase the richness and softness of the bread, but these four ingredients are the only ones necessary for making lean doughs like french breads.
It was already mentioned, but I'll say it again: Make sure to check if your yeast is dead or not. If it's old or crap (especially Active Dry, argh!) then it will be no good. Buy small quantities of Instant Dried Yeast. The yeast needs a good environment to live in, so the dough should optimally be about 80 degrees fahrenheit. Bread is harder to make in the winter and takes a lot longer. To see if the yeast is alive, stick some in a bowl with some lukewarm water (don't make it too hot!!) and a bit of sugar. The yeast should "bloom" and froth to the surface. If this doesn't happen, throw out the yeast!! As for the chemistry, it's very complex, so find yourself a very simple recipe and start there. It can either be one where you make a starter (like a "poolish" for a baguette) and leave it before adding to a bread recipe, or one where you just dump it all together without that stage. Both ways can be used to make bread. Just follow the recipe.
Unless you have a special steam injection oven you will not be able to produce crusty bread with a thin, light crust like you can buy in a bakery. You can try spraying the top of your dough lightly with a spray bottle before sticking it into the oven to delay the setting of the crust and provide a thinner, crispier crust but this doesn't always work. Make sure you let the dough double in size, and don't handle it too roughly the second time it's risen or pound all the air out of it- it'll be flat as a pancake!