A 24 inch computer monitor is good for those who do a lot of graphics work. Be sure that your desk will accommodate this, as it will be a very wide monitor. Usually, monitors come with a PC if you buy it as a package. You might be able to upgrade your monitor to a bigger one and use the credit from the smaller monitor towards your bigger monitor. That way you only pay the difference.

The function of a computer monitor is to display the results of processed data from the CPU. Touch screen monitors are both input and output devices.

how is the first computer monitor

Monitor is not plugged in or monitor is not plugged in to computer

Your tower is your computer. If you are asking if the monitor and computer have to match the answer is no. You can use any monitor with any computer.