You need something to transmit your signal. i.e. you cannot connect a piece of wire ("..hand-made antenna...")to an arduino and expect it to transmit.
You need to get a very
basic understanding of how radio works before looking for some basic tutorials.
Have a look at http://www.open.com.au/mikem/arduino/VirtualWire.pdf
to get a understanding of modulation and encoding. This library, by Mike, who also contributes to these forums, runs on basic modules but you can still learn from the code despite your aversion to modules.
If you are keen on making your own, have a look at making some basic low frequency AM type radios, e.g. http://www.talkingelectronics.com/te_interactive_index.html
and then adapting the code above to encode your transmission. You may want to look up "manchester encoding" as well.
If you want to roll up your sleeves and get arm deep in the "nuts and bolts" or radio, from hardware to software, then get started with the above and come back.
If you merely need an application to transmit a signal between two arduinos, then there are some excellent radio modules for a fraction of the cost of Xbees (and mature libraries to drive them) which you could use.