sorry f.p. assumed you had basic tools; saw, hammer, chisel, tape, pencil,they are easy to knock up, a lot easier than cutting door stop resizing doors, refitting locks/handles/hinges.
thi one locking at any angle and you will be tempted with new projects with your new found carpentry skills,top tool,good luck. http://www.diytools.co.uk/Product.aspx/!80804
unless you specifically want to make them, sawhorse brackets are available just fit timber,assemble as required,(don`t have to leave them in the garden)
When you come to the architrave cut a slight angle back on anything thats proud,if you swap for something like timber scotia you can then paint the skirting and bead it gives a much better finish, remember to fix to skirting not the floor.