If it is your first ever homecomputer just start using it,
If you are using a few standard applications (internet, email, wordprocessing) just start using it but be sure to have all credentials (username/password, adresses f.i.for the email account (same will apply for a new PC) to be able to configure it))
If you are a longterm PC user and have some specialised software packages you might want to buy a VM software (f.i. Parallels) to run those applications under a Windows environment on your Mac, in order to keep the transition smoother.
Have a llok to the apple.com, they have some tutorials for the transition.