Most welcome Sir 
Best of luck for your trip.
You can reach Hyderabad through Pak Business Express (Best train). And from there use Public transport to reach Mirpur Khas and then catch some bus or van which will take you to Mithi which is the capital of Tharparkar district.
But for tourism purpose the area which is famous in Tharparkar is known as Nagarparkar. Public vans do travel between Mithi and Nagarparkar but in limited number. You can check out our thread, we did it during Eid-ul-Fitr this year..
KTG's Trip to Nagarparkar (Land of Scorching Desert & Mesmerizing Oases)
From Nagarparkar, you can hire a 4x4 and visit Choorio village which is near the Indian border. You can see the indian side (Run of Kutch) on the other side of fence. Also you will be able to observe wildlife including peacocks, different lizards (if not in hibernation) and many small birds. There is a oasis formed known as Bhodesar which is few kilometers before Nagarparkar which is also worth seeing. And the best thing about this area is that its totally safe and crime free area.
Now, apart from Desert, Sindh has lot more to offer... So you can come to Karachi for a salt water fishing trip as we had discussed sometime before.. and from Karachi you can visit Bhambore ruins, Makli graveyard, Haleji Lake & Keenjhar Lake in a single day trip.
Another attraction in Sindh is Gorakh Hill station which is about 400 km from Karachi. I recently came back from its trip last weekend (haven't made thread yet). It is the highest point of Sindh and known as Murree of Sindh. 2 days are needed to visit it from Karachi to Karachi.
If you're into history than there are many forts also like Ranikot fort (near Sehwan, which is world's largest fort), Umerkot Fort & Naukot Fort (Both in Tharparkar dist.. see about these in our Nagarparkar Thread) and of course there is Moen-jo-Daro ruins also.
These are few places which I tried to list.. there are many more Please do contact me if you come to Karachi..
