Can anyone help me?I want to make a map that has options for starting rounds like BO2 in green run which starts in rounds 1-5-10-15-20

I don't know exactly, but if mod menus can change the round, that means there's a command to change the round.
If you can change the startup menu to change the round(might need help from a scripter), then you can make the command change the round when the game begins.

are u a scripter?

no, but with some logical thinking and research of mod tools, you can find the code, and execute it at launch.

This is what this thread looks like to me
example 1: -how do i change a lightbulb?
Answer: with some logical thinking and research of electricity, you can find the answer.

What i think he expected was more like this one below...
example 2: -how do i change a lightbulb?
Answer: you screw 1 out and screw 1 in.

I'm just saying if he looks up the code(which I can do if he wants me to), then he can put into a script that is executed at the start(absolutely no idea on how to do).  EDIT: I think I found it:   
scr_zombie_round "what round you want";zombie_devgui round        without the quotations so like round 10 would be "scr_zombie_round 10;zombie_devgui round"

One idea would be to spawn in a room at the start and they can push a button that says Round 5/Round 10/etc.

did not ABANDONED SCHOOL by jbird632 have a round selection to start with? 

im not a scriptor so not sure if it works but this might be helpful if it does:

Change start round with zombie health/speed
https://www.ugx-mods.com/forum/scripting/50/change-start-round-with-zombie-healthspeed/16473/msg157796;topicseen#new