First of all, get your entry-level license. If you're in the US (or have someone who can receive mail for you), this is relatively easy and inexpensive, and can be done completely online.
Avoid sinking a lot of money into a transceiver immediately before you've been operating for awhile and know what you're really interested in doing. You also do not need a rooftop antenna for HF (3-30 MHz; the frequencies that most often travel far) - a wire across your backyard can be quite effective.
Since you're here, I recommend getting started with digital modes like WSPR and FT8. They require a lot less power to make some surprising connections, and will teach you a lot about how propagation works and adjusting antennas, and because of the low power requirements, can be done with relatively inexpensive equipment. Some "old timers" grouch about how they're not "real" ham radio, but ignore them.
Edited to add: A good starting point that doesn't even require a license is to get an SDR receiver like the RTL-SDR and hook a long wire to it as an antenna, then listen for WSPR or FT8 signals with WSJT-X, and whatever else (other digital modes, Morse Code) with fldigi.