Config & populate a newly installed theme on my domain

Have a domain running fine on Joomla 4.2.6. I installed a theme but now wish to populate it. I do not have time to set it all up. Task would be examine my theme and supplier template, maybe install supplier sample data/layout to start and then afterwards customize more to suit my needs. In other words, setup things to visually look like how I would like it, setup menu, categories, articles and sample content/image which I will replace later myself once it is all arranged. I’m a very busy person so it may take longer at times for me to respond, including while the project is underway. I can setup ftp access, and admin access on my joomla but I do not have root access.