How Do I Soundproof A Room?

Well for soundproof room you can use blown insulation between the walls. This will help to block the sound from passing through the walls

Acoustic panels are one way to go. You can research acoustic or sound-dampening panels for residential use. Fabric wrapped wall panels and sound control doors are sold to sound recording studios, churches and concert halls. However, you can find retailers that will sell soundproofing items for home use.

I have heard that using cellular window shades works wonders.  A friend of mine has a recording studio.  He put them on his windows, but also hung some from the ceiling throughout the studio.  It worked great!  It deadened the echo.  He got his from YourBlinds.com.  Here's the link to their noise page  www.yourblinds.com
Good Luck!