What happened to Christ after he was raised from the dead?
After His resurrection, Christ dies no more; death no longer has dominion over Him. He did not stay in the tomb but lives unto God. Having died once to deal with sin, He now lives permanently unto God, never to die again.
Les explains that Christ being raised from the dead dies no more, so death has no more dominion over Him. He didn't stay in the tomb; He is no longer dead. In that He died, He died unto sin once to take care of the old people and the damning nature of mankind once and for all. But in that He lives, He lives unto God. Les connects this to verse 11, where believers are to reckon themselves likewise dead indeed to the old Adam. He notes that when we became believers, accepting the gospel and its power, we were given true free will, whereas the lost are entwined in the spider web of the devil, the flesh, and the world, and only God's power can break that. Once set free, we have the freedom of the believer, and our will is left with us.
For in that he died, he died unto sin once: but in that he liveth, he liveth unto God.