There is no requirement to start a modding queue, most queue's were started by people without any experience in modding, myself included.
Of course experience would help you getting started, but as long as you do mention that you're a beginner you should be good.
If you have a friend who has a modding queue, you could ask someone if you could join their queue to see if it works out for you.
Sort of a "trainee" situation.
Also works with other modders who aren't in your friend group, but might be a bit more difficult to get in that way.
You could just look into some queues, and look up the latest requests they got, then try to mod that without announcing yourself.
(I sometimes do that when I got some time to spare + I'm bored)
The #modreqs (in-game channel) also exists, and is used to request mods from anyone who's looking at the channel.
(You can also open the channel in your browser chats, so you don't need to stay online in the game to see messages of that channel)
If you need help setting up a queue, or need some useful tips for it let me know.
(Also, if you wanna try modding in someone else's queue you can also ask me, wouldn't be the first time I had a "mentee" in my queue)
i think ill try looking in other queue's recent posts for maps to mod for now, or in #modreqs, for now