The connector you are looking for can be found on this web site
make sure they have the one for the T-Mobile Network known as UMTS Band IV, or 1700/2100Mhz or AWS
(lots of naes for the same thing)
Depending on the desktop you have you may be able to connect the Mobile Hotspot directly to your USB port.
It will not appear as a wireless network but as a LAN network in your "connections"
If you provide the type of PC/software (Windows 7 or XP or Vista) I can help further.