Hi, not a stupid question at all! People who don't have diabetes have BG levels in the 4-7 mmol range. People with diabetes are recommended to aim for 4-7 on waking and before meals, and 4-9 mmol two hours after a meal, so your post-meal result of 11.3 was a little high, but no cause for panic. You need to look on your BG results as useful data. If this 11.3 was a one-off, don't worry. If, however, your levels are always higher than 9 mmol after eating, you should look at the type of food eaten (type and quantity of carbohydrates) and make changes to what you eat until you achieve a BG level in target. If you are taking meds or insulin, the doses may need altering if you consistently get higher levels.
To sum up - the pre-meal 5.5 was fab, the post meal 11.3 was a bit too high, but not terrible! 🙂