Some is usually used to indicate positive substance and affirmative sentences. Some can also be used in certain types of questions, such as offers and requests. Any is used in questions and negatives.
For example,
• There is some milk on the table. (affirmative sentences)
• I would like some more water. (requests)
• There are some chairs outside. (affirmative sentences)
• There is some juice in the fridge. (affirmative sentences)
• Do you have any towels? (questions)
• There aren’t any more oranges. (negatives)
• There isn't any chocolate. (negatives)
• Are there any apples? (questions)
• Is there any butter? (questions)