It is not a daft question.
You will need the delivery address at some stage, including the postcode, but you can get a lot done first.
Can you see that there are five types of item that can be sent?
It will not be a letter and probably not a tube.
So we need to know now what sort of quantity the "stuff" you are sending is, so as to decide whether it is a large letter, a small parcel, or a medium parcel.
And what choices you have to send it in, which depend on what you have got available and how much "stuff" there is.
Such as a jiffy bag or a box or just some brown wrapping paper or whatever.