At Mount Sinai, the Jews received the Torah and soon after constructed the Sanctuary there. Rather than staying in the desert where G-d provided for all their needs, they set out on a mission - to journey to Israel.
The desert is barren and desolate. Yet as the Jews traveled through the desert, they transformed it, albeit temporarily, into a settled land, a place where crops, trees, and even flowers grew. With them, they took the Torah that they had been given and the Sanctuary that they had constructed. G-d's presence, which rested within the Sanctuary brought about these positive changes in the surroundings in which they lived.
The Baal Shem Tov explains that the journeys of the Jewish people through the desert are reflected in the journeys of every individual through life. Some of the phases that we pass through may appear barren and desolate. Nevertheless, we must appreciate that this is only the external setting in which we are placed. It should not reflect our inner state - for G-d's presence accompanies us at all times and the Torah is with us in all surroundings.
Similarly, the journeys of the Jewish people through the desert also allude to the journeys of our people through the ages. Throughout history the Jews have wandered from country to country pursuing the Divine mission of revealing the sparks of holiness, which are hidden within the world's material substance, by utilizing physicality in fulfilling the Torah's commandments.
When a Jew uses an object for a mitzvah, he or she releases these hidden sparks of G-dliness and enables them to be overtly revealed. So from land to land have our people wandered, completing phase after phase of this mission.
In the process of doing so, they have made "the desert blossom." They have endowed the world with spiritual meaning and purpose, pushing it toward the culmination of this process; Moshiach's coming, when the G-dliness that pervades our existence will be apparent.
Shabbat shalom!