In an introductory note to this chapter, the Kitzur Shulchan Aruch writes that most Jews are already familiar with the prohibited labors of Shabbos and that he is only addressing common situations with which people may not be familiar. Clearly, the laws of Shabbos constitute an area requiring much greater study than this email alone will allow.
80:27 Anything that a Jew may not do on Shabbos, he may not delegate to a non-Jew to do for him. Since it is permitted for a non-Jew to light the oven in winter in order to heat the house, it became the practice for the non-Jew to put the cold food on the oven before lighting it. In this way, his intention in lighting the oven isn't to heat the food but to heat the house. Some authorities permit this so long as the non-Jew puts the food on the oven before lighting it but if his actual intention was to warm the food, it is forbidden. Other authorities forbid doing this even if he really does intend to heat the house. While the lenient opinion is typically accepted, it behooves a conscientious person to be strict on himself in cases where there is no compelling need. One should also act stringently in the case of iron ovens, which are primarily made for cooking, even though they might also be lit to heat the house.
80:28 Spilling a liquid on the ground where something grows violates the melacha of zorei'ah (sowing) because the liquid helps the plants to grow. (Other authorities say that this is a subordinate activity of choresh - plowing - because it softens the soil - Mishnah Brurah 336:26.) Therefore, one should try to avoid eating in a garden because of the difficulty in preventing liquids from spilling on the ground. Aside from that, it is forbidden to carry in gardens.