I might b a little off here but maybe U haven't activated the record enable b4 going 4 the actual record button!

On each track (or on it's track properties) .. I this the R key is the key shortcut...

so press R, then * on yer numeric keypad...

Also make sure U have yer Left locator b4 your Right locator!

DC offset.. basically is a process cause by a series of factors that generate a small error on yer recording... so in practical terms when u apply a dc correction the wave kinda get's centered back around it's timebase ( 0 db)... this a very important process that u should do b4 any editing... also after a few heavy editing/ processing (although most Plug ins r getting better and better math. algor. so the incorrections r almost 0)...
After a master I always Dc correct and then Normalize (generally to -0,5 db)


Hope this helps,

Z