Handling Plesk is Server Administration and it is your job to do it. You can't expect SM to go set up the accounts for you and effective run your business for whatever you pay them. It be cheaper than hiring someone to do it.
If you do not know how to handle it, it is not their fault. They gave you a choice to select Plesk or something else. You chose Plesk. You could have selected something else if you are not comfortable with handling something you are not familiar with.
Besides, you could actually spend sometime at Plesk website and give the Demo a spin and also download the Manual and FAQs or even participate in Plesk Forum if you are stuck. The options are all there for you. You just need to spend a little time to do it.
By the way, you can download Plesk Documentation from
http://www.sw-soft.com/en/support/plesk/
As for the rest, you should be able to find them on the navigation on this page.