quoting for jobs

Hello. I'm new to the platform and just completed my portfolio and ready to quote for work. I have a few questions. When someone is asking for a hour rate how to you fill that in on the proposal form as it asks for a total so if you put in your hour rate it looks like you are only quoting for one hour. I did think to guess how many hours it would take and put this in but not all jobs are obvious to how long they will take. When it says fixed cost of £xx in the description it that the total they want to pay for the work. Only some are ridiculously small amounts more like an hour rate.