This is such a wide and open question that might return tons of different opinions and suggestions, quite an interesting question though.
I google'd "how to launch new software and it returned as many pages. The below I found to be interesting -
Just Because You Build It Doesn't Mean They'll Come: 5 Steps to Launching Software Services Successfully
Software Service Offerings are "Real" Products.
Step 1: Complete a Soft Launch. ...
Step 2: Build a Communications Plan. ...
Step 3: Train Everybody. ...
Step 4: Secure Buy-in From the Sales Team. ...
Step 5: Execute with Precision.
More info can be found
HERE on the subject.