Fast Bounce & MP3's

I'm trying to find out how I can "instantly" bounce ALL of my MIDI trx to an MP3 so that I don't have to convert all of my unfinished MIDI trx to wav files.  I saw the Fast Bounce feature, but I never saw where it needed to be Enabled.  Also, I couldn't figure out how to use, or enable any of the encoders.  If I have to PAY for the mp3 encoder, that is just sick.
 
KC

Thanks Kalle,
 
Still have 2 questions.  1.) What FREE encoder would you recommend (or anyone following this thread), and 2.) Will it let me record MIDI to MP3.  I will poke around to see what encoders I can find.
 
KC

If what you are thinking is a way to convert MIDI backing tracks into a audio format then as Kalle has pointed out, it will have to get the audio from a synth first. 
 
Another point is it is best to export all your projects as a WAVE file first, then you can convert it to a MP3 using any software of which there are plenty of free or inexpensive choices. I use Wave Labs Batch process to convert whole albums in one pass. 
 
I do a lot of my own backing tracks  and have come up with two ways I work. 
First problem is you have to OPEN a MIDI file if you want to retain the original tempo and other settings. Importing a MIDI file into a project or template will result in only the basic data. I use a second method for this sometimes I'll explain later. 
 
So for pre made downloaded files I OPEN them to a blank screen in Sonar. 
I insert TTS-1 first. 
I then highlight whole screen "CTRL A" , go to tracks/ output and choose the TTS-1 for MIDI. 
The file should now play same as it would from Media Player. 
At this point a lazy person could now export the song as a WAVE file and move on. 
 
I'm a little more picky than that..
Now I shut off all those wheezy crappy guitar and vocal parts and mess with the sounds, 
I will also divide the drum parts into separate tracks and assign most to Session drummer. 
I will use True Pianos  and some other VST I like if needed. 
 
You will also need to add any efx busses and a master Buss. Make sure to Highlight All again and use the Track/Output/ Audio to Master. 
Myself I record real Bass because that's my style I like. Never found a MIDI bass sound that can come withing a mile of real bass running through my PA and Subs. 
 
Now I export to a 44.1/16 Bit WAVE and put in my Performance track folder. 
I then open Wave Lab and master the track for level , EQ etc. 
From there it is transferred to my Netbook for performance. 
I will also batch process my performance tracks to 160 kbps MP3 as a back up that goes on a MP3 player. And I still convert them on to my Sony Walkman MINI Disk player. Three players ready at each show. Never had the netbook crash but! 
 
This is as fast as it's going to get if you want some kind of quality control. Otherwise record to Audacity with "what you hear" and use Media Player.