An alternative to davidjosepha's method, j_menz, is this online keyboard:
https://www.lexilogos.com/keyboard/russian.htm It has the advantage of not making you learn a whole new layout in order to write in Russian, since most of the letters you type on your standard English keyboard will correspond to their Russian equivalents, so if you type, for ex., ' V ', the letter ' В ' will appear; if ' Z ', ' З ' and so on.
And the ones that do require some memorizing are not that hard because all of them are logical enough, phonetically speaking. For instance, to write ' Ж ' you need to type ' Z + H ', which is the way that Russian letter is usually transliterated into the Latin alphabet; if you want to write ' Щ ' you need only type ' SH + CH ', etc.
As someone who's studying a number of languages with different writing systems (Russian among them

, I can tell you it's
very handy and the best tool of this kind I've found so far because it really makes things much easier, and the good news is there are online keyboards for many more languages on that same site, just left-click where it says 'multilingual keyboard' (at the top of the page, in orange font) and voilà

: Georgian, Korean, Arabic, Hebrew, Pashto, Japanese (using both, the syllabaries,
and the kanjis), Chinese (using radicals or Pinyin, whichever you prefer) Coptic, and many more are there, too, and they all follow that same principle of always trying to save you the trouble of learning a completely (or almost) new keyboard layout.
Best!
M.W.