Where can one find information about the history of Old English?

Your problem is that "Old English" is a generic term which really covers a variety of dialects. Although by,say, the time of the Battle of Hastings, there was probably a single recognisable language which would be fairly universally recognised as "Anglo Saxon" (i.e. Old English), the further one goes back in time the more the regional dialects were distinct languages in their own right.

The dialect which is normally taught as "Anglo Saxon" (or Old English) is in fact Early West Saxon, mainly because that is the version used in the Anglo Saxon Chronicles, but at the time there were distinct variations in the languages of Northumbrian, Mercian, Kentish and doubtless others which have disappeared in the mists of time.

The further one goes back, i.e. to the period of the initial Germanic migration to England (broadly 400 - 500 AD) the more we would be deal ing with essentially separate languages, depending on whether the particular tribes were constituted from the Angles, the Saxons, the Friesians or the Jutes. Their geographic origins ranged across a swathe of Europe from present-day Denmark, through Germany and into Holland, so it is not surprising that a variety of languages made their way into England to be loosely consolidated, centuries later, into "Old English".

So to go back your original question, there is no simple answer to the history of a single Old English language as it rapidly splits up into separate liguistic and geographical trails. A useful basic starting point is the website athttp://www.geocities.com/blondelibrarian/literaryexplorer/English.HTML

Hope this is of some use.