From Delhi, Ladakh splits into two completely different trip styles. Flying direct to Leh takes roughly 1.5 hours and is by far the most common choice, since it avoids the long acclimatization-heavy road journey - though you still need at least one full rest day in Leh before heading anywhere higher.
The road-trip version instead routes through Manali (itself reached from Delhi as described on our Manali page) and then the Manali-Leh Highway, a two-day drive over some of the highest motorable passes in the world. This route is only open roughly June to September and is popular with self-drive and motorcycle groups who want the journey to be part of the experience, not just a means to an end.