Assuming you have installed a full server product, you should have also installed the client tools, in particular SQL Server Management Studio (SSMS). If you didn’t, go through the installation again and add them.
Once you have SSMS installed, you will find most of the basic functions available with a click or two in the GUI.
If this is more than a passing interest, you might invest in a book but for the absolute basics, I found a light beginner tutorial here:
and a little more in depth here: