Yesterday arrived my GPS receiver, an Acer v200 Travel Companion, which I bought through eBay. On the evening, I read the manual and walked around some streets near my place, logging my track.
Today, I found out that in order to convert my trace (saved in a .dat file) to GPX format I had to use the very latest version of GPSBabel (1.3.5, released just three days ago -- wow! I've been lucky). It's not in Debian yet, but it compiled without any hassle :-)
First opening of JOSM was somewhat frustrating, but PerroVerd was very helpful, explaining me the basics. In no time I was creating objects and labelling them. Just a while ago, I submitted my first upload.