Jackhammer and TrenchBroom are the most commonly used map editors.
http://www.celephais.net/board/view_thread.php?id=60335&start=1284
http://www.celephais.net/board/view_all_news.php
Also: you are very new, the emphasis of this thread is more self-help and a good storage of information and helping someone already familiar with modelling figure out how to get them into Quake (which can be quirky). You can make requests, but the thread info also cautions those "may well be met with silence".
(i.e. if you are real lucky someone might "do it for you", but those would probably be something like a knight holding a different weapon or something simple and someone owes you a favor or likes your existing body of Quake maps that you have built).
You might consider getting familiar with map editors, maybe play some Arcane Dimensions (its open source, has a lot of monsters) and do some QuakeC tutorials.
http://www.celephais.net/board/view_thread.php?id=61270
https://www.youtube.com/watch?v=8YsKfkV6LV4
Doom monsters are just sprites right? Quake is far more complex than Doom and you probably should level up on mapping and QuakeC before walking down that hard road. Arcane Dimensions has quite a number of new monsters and the source code is with the download.
Arcane Dimensions has so much it can do, it should entertain you.
There is also Quoth:
https://www.quaddicted.com/webarchive/kell.quaddicted.com/ (Arcane Dimensions has some of Quoths monsters in it).