It's double entry accounting, so when you spend money, you have to give an "account" that you spent from and an "account" that you spent to. For example, if you wanted to track somethings but not others, you can keep your ATM slips. When you withdraw money you simple add a transaction from your "bank account" to your "cash account". Then let's say you wanted to keep track of your spending at restaurants, but didn't care about anything else. In that case you keep your restaurant receipts. You make a transaction from your "cash account" to your "restaurant expense account". At the end of the week, you look at how much money you have left in your pocket. You can enter a transaction saying you have that much left and (with ledger anyway) can tell it to put the difference in your "miscellaneous spending account".

Later your can run a report which shows how much money you spent. It will tell you how much you spent on restaurants and how much you spent on "miscellaneous spending". If you think that you want to explore what you are spending on "miscellaneous", then you can keep receipts for those things and start an account for it.

Remember the point is simply to let you measure things. It's up to you to decide what's important to measure. If you don't think it is important to measure anything, then the accounting package is very accommodating. You just don't use it ;-)