Привет,
Christineka!
If you let us know whether you use a PC or Mac (and what version of Windows or MacOS is installed) someone here should be able to explain to you how to set up your own computer so that you can instantly toggle your own keyboard between English and Cyrillic input.
In the meantime, you can use a "virtual online keyboard," such as
this one. Click on the keyboard with your mouse to select letters, or use the keys on your keyboard (but it seems that you have to do one click with the mouse in order to activate the keyboard entry). Then just copy and paste the Cyrillic content into the MasterRussian text-entry window.