First of all you need to know about the duties of an administrative assistant only then you will be able to make a manual for the post. The first thing he should do is to coordinate the work flow and also have to take care of the progress about the deadlines. There are a lot of other things to ensure also which is not possible to describe here. I am going to give you the address of a website that can be helpful to you to know the responsibilities and the address is following: www.iaap-hq.org/researchtrends/jobdescriptions.htm.
When you come to know about the responsibilities you can write down all of them and according to your condition you can reorganize them and make it compatible to the needs of your office and then can circulate it to make the concerned person comply with it.
When you come to know about the responsibilities you can write down all of them and according to your condition you can reorganize them and make it compatible to the needs of your office and then can circulate it to make the concerned person comply with it.