Hey Niyumi!
I second Just ChiII in his assessment that it doesn't matter what DAW you use (within reason, of course - certain DAWs that have very specific specialties would be too limited for "general audio and midi production").
Outside of the DAW, there is a bunch of software and hardware that play a part in the making of music. That greater ecosystem may include samples (the actual sounds you use, often "multisampled", mapped across the keyboard, so you can play them using the DAW or midi keyboard), a midi controller (keyboard to input music into the sequencer), sound interface, plugins, etc.
I don't know for sure whether FL Studio can do orchestra, but I can imagine that it does. See what sounds/samples come bundled with it. In time, you may find yourself wanting to expand your palette of sounds to include better or more varied samples.
If you want to produce orchestral music with a computer, you will need to harm yourself with patience, it's almost like learning how to play an instrument. Ultimately, what matters most is what YOU have to contribute as a composer - the stories you want to tell, the colors you like, etc. Make sure to cultibate that first and foremost (and study/listen the masters!).
Good luck in your endeavors!
Ed the Conqueror