How can l assemble its engine

@declare this is really not how we work on here. You are giving us 2 words about what you are wanting to accomplish. This is one of the cases where you really need to be more descriptive. If you want to do a complete overhaul of your engine, you need to tell us that and need to have a bit of experience with that too. If you just want to assemble the engine, then we would need to know how far it has been disassembled. You also need to tell us what engine your Funcargo is having.

You can always check the 1999 2007 Toyota FunCargo Manual or use the Toyota 1NZ FE EngineToyota 2NZ FE Engine manuals depending on what size your engine is.