Hi ZZM....glad you've done all the lessons ....sure to get big nods of approval from the members here. You will find a whole section on this subject in the learning centre but if you are really stuck and can't sort it out from there well.......
.....this might get you started using flight plans, and flying IFR under ATC is my favourite way of going about it........you can fly in thick fog this way

Get your self to the Create a Flight set up screen and select the usual stuff ..aircraft/weather/airport etc..then on the same page click the FLIGHt PLANNER button....
...select a departure airport and a destination airport and then select the type of flight plan you want...click the IFR button eh?..choose direct GPS as the routing and finally click the Find Route button.
click Save and select the Flight Simulator Files, folder in the right hand side ..click ok. to save it there.
click Load and select your saved flight from the left hand side and click ok...
FINALLY click OK to quit the set up stage and when asked if you want to move to the starting airport click YES... the FLY NOW button will take you there.
Start up ATC by pressing the accent '