Templates for Power BI

I'm very new to power BI so this might be a stupid question but can't figure it out. I have a summer job where I will analyze data from a folder with various datasets. I want to create a standard design template so that every page inside the powerBI dashboard will easily implement the same design. I've tried looking on youtube, where they want me to create a dashboard with one dataset, save this as a template and then create a new parameter called for example "filepath" and change the document's source path to the parameter? I can't get it to work and can't see how this template can be implemented to design another dataset inside the same dashboard. Can anybody help me?