In Canada, a Will can only be legitimately written if you are in the army on duty, married or a sailor at sea. If it is a simple Will, meaning the only beneficiary is a spouse, it can be drafted by a notary public. Any complex Wills with serious estate issues must be written by a lawyer.
I recently completed my Wills and Estates course through Okanagan College and I work for the largest firm in my area. Depending on the area you live in, you need to visit the law society site for your location. There you will find information on what clauses are required.
A Will cannot be witnessed by anyone who is a beneficairy under that Will as they may influence what is left to them. In a Will you are required by law to provide for persons in this order: spouse, children (if your childeren pass you can leave gifts for their children (grandchildren), parents, siblings, nieces and nephews. If you Will becomes void by being witnessed by a beneficiary or if your executors pass and you fail to name an alternate executor, you die intestate.
If you die intestate then a court appointed executor will be named for your estate, that person will then be called the administrator.
You are required by law to provide for your spouse first as you swor your vows to care for them.
My suggestion to you is to talk to a lawyer. I know that our office charges a flat rate for Wills and it is not that expensive. Plus they have fire proof cabinets where Wills are kept in a secure location so you have the guarantee that your Will is safe and secure.
If you would like a template for how to draw a Will, visit the law society website for you area. It is the best way you can get a better understanding on your own. Hope this helps!