There is a Plane command and also an Axis command that will do what you want. I'm surprised you haven't learned about Plane yet - it is a very common tool to define planes for sketches and other purposes. Offset planes are probably the most common. If you can't find the icon (it's available in the Part Design workbench and also the Wireframe and Shape workbenches), you can always type c:Plane down in the lower-right corner (what's called the "Power Input" box) to create a new plane.

IMO, Axis aren't used as much as planes, but they probably are more powerful.

Look in the Online Help files for instructions on both Planes and Axis Systems.

Here's a Tip: always use positioned sketches, instead of the default sliding sketch.