The topic line says it all.
I find Upwork to be very confusing around this and need some instructions on what to do.
You log hours either using the desktop tracker or manually. You can't do that until you have a contract in place. Please go to Help and Support and read the relevant information about setting up contracts and getting paid. There are also articles pinned to the top of the New to Upwork discussion board in this forum.
Please go through the guides, tutorials, courses, videos, Help articles and Community discussions compiled in this thread, designed to help freelancers find success on Upwork and afterwards, if you have any questions feel free to follow up here and we'll gladly help you with them.