You must watch my free lectures (and if necessary the relevant Paper F2 lectures, because this is revision of F2). This is all explained in the lectures and I cannot type them all out here!!
You use annuity tables when it is an equal cash flow for several years. For other flows you discount them individually using the present value tables.
Do watch the lectures – they are a complete free course for Paper F9 and cover everything needed to be able to pass the exam well.