MySQL:Only one user writing into table at the same time?

Hi @ll! I'm preparing for my final examination, where I have to set up an intranet database application running under linux. I will use php and mysql. But now I heard, that mysql cannot handle more than one user writing into the table at the same time. But I will develop an authoring system, which must be able to let more than one user write. So what happens, if really two or more users try to write into a table? Will there only be a delay or even a system crash? I heard about a posibility to configure mysql for that problem, so that multiple users-writings work. Does anybody know where to get a description of this configuration? Can I use certain php-commands to go around this problem? Please help me! THX, Ollie.