Sorry for my stupidity, but after 4 hours I still cannot figure out to build a project to give me a useful Gantt chart. Did anyone ever produce a user manual for us simple folk

I have made the process but i can only fill in start dates and only one of the process/ tasks show in the gantt chart. Finding it hard to follow the instructions in the software as a lot of the terminology is double dutch to me.
Thanks for anyones help in advance..