Read up on stuff on the internet, and do the flying lessons the flying lessons will teach you how to fly ILS, VOR. As for holding patterns you just fly around a certain VOR etc.. Now if you really want to get realistic buy a payware airplane they cost anywhere from $30-70 for the good ones. PMDG are the best IMO but too expensive. Flight 1 sells LevelD 767 which is a great one. The best one I have ever had is Digital Aviation Fokker 100/70
Now these planes take days if not a week or maybe two of studying and flying around until you can really fly them, they have everything, FMC,APU,Pressurization etc.. There is no GPS here. These are the type of planes you can fly Vatsim commercial flights in as they have all the SIDs and STARS in the FMC etc.. Just be patient and fly around and try to learn new things.
I been on FS
since FS2000 and I continue to learn new stuff every time I use the program.
As for VATSIM I heard it is very realistic and I would love to try it one day but I just don't have the time, patients or equipment to set up all the stuff for the live ATC etc.. It seems like it would be awesome. But yes you do need to know a lot about flying to have a good time there.
"It was just four of us on the flight deck, trying to do our job" (Captain Al Haynes)