A website is not really what you need. The book is T. Harry Williams, "Lincoln and His Generals." President Abraham Lincoln was the commander-in-chief and so the final decisions were his. He had a good understanding of military strategy and tactics.. Lincoln had to prod his generals. He had a good political understanding that the Congress and people would not stand for inaction. Lincoln recognized an important military fact that waiting until conditions are perfect means never acting.
After a minor victory in West Virginia Gen. George McClellan emerged as the choice to head the Army of the Potomac. McClellan could train troops, but would not fight. Lincoln recognized this. He still let McClellan carry out his own strategy such as Seven Days and the Peninsula Campaign. But Lincoln saw the chief requirement for victory is to destroy your opponents army, manpower, and not occupy territory. McClellan did not recognize this, and after giving him a fair chance, sacked him for good when the President saw he would not fight.
In short, Lincoln's understanding of the military grew during the war. Unlike President Jefferson Davis of the Confederacy he saw how critical the West (this was territory outside of Virginia) and Mississippi River were. He did have a hard time finding good top commanders, but finally did with Ulysses Grant whom Lincoln appointed to head of the whole U.S. Army and Gen. William Sherman in the West. Generals Grant and Sherman understood that war is hell, and destroyed the South as well as winning battles. They beat the Confederacy down to a helpless nub. Earlier, with his lesser generals Lincoln became more actively involved in strategy. However, when Lincoln found a first-rate general who would fight Grant, he fully backed him and basically let him alone to perform the tactics and actions that were effective.
Lincoln showed patience with Generals such as Burnside, Hooker, and Meade, but when they would not act, he found a general who would. That man was Grant, who also let Gen. Sherman fight as he wanted to in the West. In the last year of the war, the two generals and Lincoln were a highly effective team. Lincoln always kept informed of developments, but saw with Grant and Sherman no prodding or much advice was useful. But even with subordinate generals, such as Gen. George Thomas, Lincoln performed the necessary pushing many such commanders needed,.
I highly recommend "Lincoln and His Generals" by T. Harry Williams.