"I should say, my IT skills are close to zero."

I bet that translates to "I'm using Microsoft Windows". In that case, you plug it in and follow instructions such as these:

How to change keyboard language in Windows

Change your keyboard layout

This will give you an icon to click to switch between English and Russian layout. Windows offers serveral different cyrillic layouts, I think the correct one is called Russian / Russian as opposed to such layouts as Russian / Ossetian etc.

Should you have any problems setting that up, you can ask again, but tell us which version of Windows you're using exactly because some things may be different from version to version.