"HOWTO do Linux kernel development" (title of your link) is not the same question as "Which environment to use to develop real time with other developers" (same question different phrasing). I don't know how you got the impression that the OP wants to do Linux development anyway, and if you wanted to give him inspiration that link has nothing to teach about developing in a team.. 0_0
By the way since I'm here anyway, I don't know much about this (though I know Visual Studio has a feature called LIVE SHARE which was made especially for your requirements). I have always used codeshare while I was programming with my buddy (it was a one time thing though). I know there are some other websites but I don't know if that's what you're looking for because they weren't meant for "team development" per se they were made for things like interviews.
So instead use your favorite search engine (just not Bing, please, even if its your favorite) and look it up! You might find something like Live Share on Visual Studio, maybe even on your IDE!
it depends on the team, the size, and so on. My first job, we had 5 developers or so (it varied over the decades by a little) and we mostly just coordinated the old fashioned way -- we talked to each other and kept pretty good tabs on who was playing with what code areas at any given time. There were a few incidents, nothing a half hour and windiff couldn't solve, and I would estimate we didnt have more than 2 of those in a year, all minor.
I now work for a gigantic company and they keep all the code in a repository that we have to check in and out of; it manages version control and who did what, when, why, etc. Its extremely annoying but its really the only way for a team of 100+ developers to keep it sane.
Most of the tools work that way... one person can check code out for editing, and no one else can edit it until they check it back in. If someone keeps it too long, you probably need to talk to each other a bit. These ideas have been pretty standard for approaching 50 years now, so you should be able to find out a great deal about the process with a little searching as others have said. GIT and opensource have taken it to new levels but the underlying principles are pretty much the same old things.
Is there any possible Tool that we can develop at the same time in One Projekt with c++?
If you're looking for particular tools, look into version control systems like git and perforce. In perforce at least, you have the notion of "checking out" files, and re-submitting them to the server. When you check out a file for edit, other people can see that you're working on a particular file. Big projects should have different logical modules broken up to different files to minimize merge conflicts (two people working on the same file at the same time).